ren'youkei 連用形

In Japanese, the ren'youkei 連用形 is one of the six basic inflectable forms of verbs and adjectives.

For example, in yomimasu 読みます, "to read (polite)," and yomitai 読みたい, "want to read," the yomi 読み is the ren'youkei form of the verb yomu 読む, "to read."

Conjugation

For reference, how to conjugate the ren'youkei:

*Ren'youkei* Conjugation Table
Irregular Verbs
	~masu ~tai ~nasai ~sugiru ~yasui	~tara (~dara) ~tari (~dari) ~ta (~da)	~te (~de)	aru nai gozaimasu*	naru zonjimasu*
kuru くる	ki~ き～
suru する	shi~ し～
iku 行く	iki~ 行き～	it~ 行っ～
Godan Verbs
kau 買う	kai~ 買い～	kat~ 買っ～
kaku 書く	kaki~ 書き～	kai~ 書い～
oyogu 泳ぐ	oyogi~ 泳ぎ～	oyoi~ 泳い～
korosu 殺す	koroshi~ 殺し～
katsu 勝つ	kachi~ 勝ち～	kat~ 勝っ～
shinu 死ぬ	shini~ 死に～	shin~ 死ん～
asobu 遊ぶ	asobi~ 遊び～	ason~ 遊ん～
yomu 読む	yomi~ 読み～	yon~ 読ん～
kiru 切る	kiri~ 切り～	kit~ 切っ～
Ichidan Verbs
kiru 着る	ki~ 着～
taberu 食べる	tabe~ 食べ～
Adjectives
kawaii 可愛い		kawaikat~ 可愛かっ～	kawaiku~ 可愛く～
kawaii かわいい				kawayuu* かわゆう
kirei na 綺麗な		kirei dat~ 綺麗だっ～		kirei de 綺麗で	kirei ni 綺麗に
Jodoushi 助動詞
masu ます		mashi~ まし～
desu です		deshi~ でし～

As you can see above, literally the only thing all inflectable words have in common is that the past form is constructed from the ren'youkei plus the ~ta ～た jodoushi 助動詞. Everything else is the messiest mess.

音便

For godan verbs, the ren'youkei form always ends in ~i, except when it doesn't.

When it comes before ~ta ～た, ~te ～て, ~tara ～たら, ~tari ～たり, and so on, the conjugation of godan verbs suffer a change in pronunciation called onbin 音便.

There are four onbin in total: i-onbin イ音便, sokuonbin 促音便, hatsuonbin 撥音便, and u-onbin ウ音便. Only the first three affect the ren'youkei of godan verbs in standard, modern Japanese.

For example, the ren'youkei of kaku 書く, "to write," is kaki 書き, plus ~ta ～た, you get kaki-ta 書きた, which undergoes i-onbin, turning into kaita 書いた, "wrote." The kaki became kai due to onbin.

This kai 書い is called an onbinkei 音便形 when differentiating from the ren'youkei kaki 書き.

Besides this, some godan verbs suffer renjoudaku 連声濁, which turns the ~ta, ~te jodoushi into ~da, ~de. For example: oyogu 泳ぐ, "to swim," becomes oyoida 泳いだ, "swam."

The u-onbin affects i-adjectives coming before the verbs zonjimasu and gozaimasu. For example: arigatai ありがたい, arigataku gozaimasu ありがたくございます, arigatou gozaimasu ありがとうございます.

In archaic Japanese and in some regions of Japan, u-onbin also affects verbs. For example: tanomu 頼む, tanomi-te 頼みて, tanoude 頼うで.

Usage

The ren'youkei form is used in a diverse number of ways.

Noun Form

The most basic way to use the ren'youkei is as a noun form. That is, you can use the ren'youkei of a verb to refer to the act of the verb.

shibaru
縛る
To restrain. To tie up with rope. (godan verb.)
shibari
縛り
A restraint. Tying.

This is called tensei meishi 転成名詞, "transformation noun," because the verb transforms into a noun.^{(高橋, 2011:15)}

Since this is a noun, it can be be qualified by adjectives and pronouns.

kanjiru
感じる
To feel. (ichidan verb.)
kono kanji
この感じ
This feeling.
ii kanji
いい感じ
Good feeling. (used when something seems good for you.)

Depending on the word, it translates to English as a gerund, ending in "~ing," but that doesn't always happen.

The usage of this noun form is limited. It turns the verb, and the verb alone, into a noun. There are many cases where you need to turn the whole clause into a noun, then the noun form isn't used, a nominalizer is used instead. For example:

watashi wa {neko ga suki da}
私は猫が好きだ
{Cats are liked} is true about me.
I like {cats}.
- This is a double subject construction.
- The noun neko is the small subject.
*watashi wa {manga wo yomi ga suki da}
~~私は漫画を読みが好きだ~~
(wrong.)
- Since neko is a noun, it makes sense we can replace it by another noun.
- However, we can't replace neko by manga wo yomi, because manga wo yomi isn't parsed as a noun clause.
- Instead, we have to do this:
watashi wa {{manga wo yomu} no ga suki da}
私は漫画を読むのが好きだ
{The act of {reading manga} is liked} is true about me.
I like {the act of {reading manga}}.
I like {reading manga}.
- In this sentence, the relative clause manga wo yomu qualifies the no の nominalizer in order to refer to "the act of reading manga."
- The ren'youkei isn't used in this sort of sentence.

Even if the clause doesn't have arguments (like the direct object manga wo), it's safer to just avoid the ren'youkei in general, using a nominalizer instead.

That's because the tensei meishi can be idiosyncratic, that is, the meaning of the noun can be different from what you'd expect from the meaning of the verb that the noun derives from.^{(谷口, 2007:64, as cited in 高橋, 2011:18)}

For example:^{(高橋, 2011:18)}

kare wa {{hanasu} no ga hayai}
彼は話すのが早い
{The act of {talking} is fast} is true about him.
His talking is fast.
He talks fast.
kare wa {hanashi ga hayai}
彼は話しが早い
{The talking is fast} is true about him.
He understands things quickly.
- With the ren'youkei, the meaning is completely different from what you'd normally expect.
- Instead of physically speaking quickly, the idea shifted into conversations with him ending quickly because you don't need to explain stuff a lot, he gets what you mean with impressive speed.

Sometimes the noun form is spelled without okurigana. This is specially the case with verbs whose noun forms are well-established as nouns.

hikaru
光る
To shine.
hikari
光
Light.

hanasu
話す
To talk.
hanashi
話
What has been said.
A story.

After の

A common pattern is replacing the ga が particle by the no の particle to refer to the action of the subject by turning the object into a no-adjective. Observe:

shishou ga oshieru
師匠が教える
Master teaches.
shishou no oshie
師匠の教え
The teachings of master.
What master taught.

Tarou ga kangaeru
太郎が考える
Tarou thinks.
Tarou no kangae ga tadashii
太郎の考えが正しい
The thinking of Tarou is correct.
The way that Tarou thinks is correct.
Tarou's thoughts are correct.

kodomo ga asobu
子供が遊ぶ
Children play.
kodomo no asobi
子供の遊び
The playing of children.
The way that children play.
A game that children play.

neto-juu ga susumeru
ネト充が勧める
A net-junkie recommends.
- neto-juu
  ネト充
  Someone satisfied with their Internet life. See also: riajuu リア充.
Neto-juu no Susume
ネト充のススメ
The Recommendations of a Net-Junkie.

An idiosyncratic example:

watashi no yomi ga tadashikereba...
私の読みが正しければ･･･
If my reading is correct...
If my guess is correct...
- Here, yomi 読み, "reading" means how someone has read the situation, specially how the situation will develop in the future. It means someone's guess.
- It normally doesn't mean how someone has read a word, text, or book.

For suru-verbs, shi し should be tensei meishi of suru する, however, in the case of possessives like these, you just use the suru-verb without suru.

Kino ga tabi suru
キノが旅する
Kino journeys.
Kino no Tabi
キノの旅
The Journey of Kino.

It's also possible to change the adverb that modifies a verb into an adjective that modifies the noun.

kataku mamoru
固く守る
To defend solidly.
mamori ga takai
守りが固い
The defense is solid. (i.e. it's not sparse, it's impenetrable.)

kanojo ga yoku sodaterareta
彼女がよく育てられた
She was raised well.
kanojo no sodachi ga ii
彼女の育ちがいい
Her raising is good.

Before に

When the noun form of a verb is marked by the ni に particle, it can express the objective of another action. For example:

tasukeru
助ける
To help.
tasuke ni iku
助けに行く
To go help.

asobi ni kita
遊びに来た
Came [here] to play.

kenka suru
喧嘩する
To fight.
kenka shi ni kita
喧嘩しに来た
Came [here] to fight.

The ren'youkei also comes before ni に in one of the many kinds of keigo 敬語, "respectful language," in which the o 御, go 御 prefix comes before the ren'youkei, forming the pattern o-__ ni naru お～になる.^{(寺村, 1982, as cited in 澤西, 2003:47; 野口, 南條 and 吉見, 2007:3)}

The exact prefix usually depends on whether it's a native Japanese verb, or a Chinese-based verb (suru-verb), although there are exceptions to this rule.

nomu
飲む
To drink.
o-nomi ni naru
お飲みになる
(same meaning, but respectful.)

taberu
食べる
To eat.
o-tabe ni naru
お食べになる
(same meaning, but respectful.)

kounyuu suru
購入する
To purchase.
go-kounyuu ni naru
ご購入になる
(same meaning, but respectful.)

Note that there are also other respectful expressions that can be used instead, like meshi-agaru 召し上がる, "to eat," "to drink."

Before はしない

The noun form can also be marked as the topic by the wa は particle,. This phrase is then followed by the suru する auxiliary in order to conjugate it as a verb.

Most of the time, it's going to be in the negative, shinai しない, because it'll be denying a presupposition. For example:

kega suru
怪我する
To be injured.
kega wa suru kedo, shini wa shinai
怪我はするけど死にはしない
Being hurt, [you] will, but dying, [you] won't.
You may get hurt, but you won't die.

The ya や particle commonly replaces the wa は particle in this usage. There's no difference in meaning, so it's possible that ya や is just an easier way to pronounce wa は. For example:

Manga: Naruto ナルト (Chapter 12, 終わりだ！！)

ore no
nakama wa
zettai korosase ya
shinaai yo!
オレの仲間は絶対殺させやしなーいよ！
[I] absolutely won't let [you] kill my nakama!
- korosaseru
  殺させる
  To let [you] kill.
- korosasenai
  殺させない
  To not let [you] kill.
- korosase wa shinai
  殺させはしない
  To let [you] kill, [I] won't.

Before もしない

As usual, anything that can be marked by the wa は particle can also be marked by the mo も particle.

nigeru
逃げる
To run away. To escape.
kakureru
隠れる
To hide.
ore wa nige mo kakure mo shinai
俺は逃げも隠れもしない
I won't escape, and won't hide.
I'll neither run away nor hide.
- I'm no coward. Bring it on!

In Compounds

Many words are noun compounds created from a verb in noun form. For example:

kesu
消す
To erase.
gomu
ゴム
Rubber.
keshi-gomu
消しゴム
Erasing rubber.
An eraser. (like, that erases pencil writing.)

odoru
踊る
To dance.
odori-ko
踊り子
Dancer. (generally a girl, like a belly dancer.)

yomu
読む
To read.
kaku
書く
To write.
yomi-kaki
読み書き
Reading and writing. (generally used to talk about learning how to read and write.)

yaku
焼く
To burn. To cook. To grill. To fry.
(literally any word ending with ~yaki.)
tako-yaki
たこ焼き
Octopus dumplings.

iu
言う
To say.
ii-kata
言い方
Way of saying.
The way you say something. (generally used when someone speaks rudely.)

tsukau
使う
To use.
mahou-tsukai
魔法使い
Magic-user.
tsukaima
使い魔
Used demon.
Familiar spirit.

The ren'youkei is subject to changes in pronunciation like when used as a suffix.

korosu
殺す
To kill.
hito-goroshi
人殺し
Person-killer. A murderer. (rendaku.)

kataru
語る
To speak of.
mono
物
Thing.
monogataru
物語る
To attest (a fact).
monogatari
物語
A testament.
A story.

kurasu
暮らす
To reside. To live (somewhere).
Gakkou-Gurashi!
がっこうぐらし！
School-Living!
Living at School!

There's a class of auxiliary adjectives and auxiliary verbs that attach to the ren'youkei, forming "compound adjectives," fukugou-keiyoushi 複合形容詞, and "compound verbs," fukugou-doushi 複合動詞. Some examples include:

yomi-yasui
読みやすい
Easy to read.
yomi-nikui
読みにくい
Hard to read.
ari-gatai
有り難い
Unlikely to have. Hard to come by.
Something you're grateful for getting.
ii-dzurai
言いづらい
Hard to say.

yomi-hajimeru
読み始める
To start reading.
yomi-oeru
読み終える
To finish reading.

koroshi-tsudzukeru
殺し続ける
To continue killing. To keep killing.
koroshi-sokoneru
殺し損ねる
To fail to kill.

benkyou shi-naosu
勉強し直す
To study once over again. (because the first time you studied wrong.)
benkyou shi-sugiru
勉強しすぎる
To study too much.

~komu
～込む
(to forcefully cram into somewhere.)
fumi-komu
踏み込む
To step into (a territory, a land mine).
hairi-komu
入り込む
To enter into (a cramped place).
oshi-komu
押し込む
To press onto (to pressure).
tanomi-komu
頼み込む
To request (assertively).

The auxiliary ~nasai ～なさい is an abbreviation of the imperative nasaimase なさいませ, which is the ren'youkei of nasaru なさる, "to do," plus the imperative of ~masu ～ます. It's used to order people around.

damaru
黙る
To be silent.
To shut up.
damari-nasai!
黙りなさい！
Silent!
Shut up!

Nominalized Adjectives

In general, the ren'youkei of adjectives can't used as a noun form. However, the ren'youkei of i-adjectives, which ends in ~ku ～く, can be used as a noun under specific circumstances.

The adjective must be spatiotemporal, that is, it must mean space or time, near, far, soon, late, and so on. It must come immediately before a particle. And the particle must be kara から, made まで, e へ, or ni に. It can't come before ga が or wo を.^{(Larson and Yamakido, 2003)}

For example:^{(Larson and Yamakido, 2003:2)}

Tarou ga tooi basho e itta
太郎が遠い場所へ行った
Tarou went to a distant place.
Tarou ga tooku e itta
太郎が遠くへ行った
Tarou went to a distant [place].

kono densetsu ga furui jidai kara aru
この伝説が古い時代からある
This legend exists since an old era.
kono densetsu ga fukuru kara aru
この伝説が古くからある
This legend exists since an old [era].

Conjunctive Form

The ren'youkei can express that one action occurred concurrently or in sequence with another. Since in this case the ren'youkei connects one clause to another, it works like a built-in conjunction, hence the term conjunctive form.

Observe the examples below:

manga wo yomu
漫画を読む
To read the manga.
manga wo yomi, anime wo miru
漫画を読み、アニメを見る
To read the manga, and then watch the anime.

shiru
知る
To know.
onore wo shiri, teki wo shireba, hyakusen ayaukarazu
己を知り、敵を知れば、百戦殆うからず
Knowing thyself, and knowing [thy] enemy, fear not one hundred battles.
If you know your allies, and you know your enemy, you don't have to fear the result of one hundred battles.
- Sun Tzu, The Art of War.

Although the ren'youkei looks like the same as the English adverbial participles, which ends in "~ing," it doesn't work exactly like them.

For example, you can say "reading manga is fun," and then the phrase "reading manga" is a noun phrase, a gerund phrase, which is similar to how the noun form works.

However, when you say: "reading manga, I watched anime," the phrase "reading manga" works as an adverb for the matrix verb "watched." You watch anime. How? Reading manga. These two events are happening simultaneously, at the same time.

This is different from how the ren'youkei works in Japanese. If you say manga wo yomi, anime wo miru, one thing doesn't modify the other. You just read manga first, then watched anime later.

The ren'youkei can also mean two things are happening concurrently, rather than in sequence. When this happens, the order of the clauses doesn't matter, and you can switch one by the other. Observe:

teki wo shiri, onore wo shireba, hyakusen ayaukarazu
敵を知り、己を知れば、百戦殆うからず
Knowing [thy] enemy, and knowing thyself, fear not one hundred battles.

Above, we switched teki and onore, but the meaning is the same, because you must know both things at the same time. Do note that knowing one thing doesn't affect knowing the other thing, so the two events occur concurrently in parallel, isolated from each other.

Syntactically, it's perfectly fine to chain two or more ren'youkei creating a long sequence of events. But note that if you do that, your sentence is going to get very long, and it's going to sound weird, no matter the language.

ha wo migaku
葉を磨く
To brush [one's] teeth.
kao wo arau
顔をあ洗う
To wash [one's] face.
ha wo migaki,
kao wo arai,
asa-gohan wo taberu
歯を磨き、顔を洗い、朝ごはんを食べる
Brush [one's] teeth, wash [one's] face, eat breakfast.

Many of the verb-verb compounds work in a way similar to the conjunctive form, in the sense that the second verb happens after the first. For example:

hiku
引く
To pull.
komoru
こもる
To not leave a place where you're into.
hiki-komoru
引きこもる
To pull yourself into somewhere, and then not leave.
To shut yourself into somewhere.
hiki-komori
引きこもり
A shut-in.

Before ながら

The ren'youkei of verbs can come before the conjunctive particle nagara ながら, which means that two events are occurring concurrently, one thing happens "while" another thing also happens.

tabe nagara terebi wo miru na
食べながらテレビを見るな
Don't watch TV while eating.
manga wo yomi nagara ongaku wo kiku
漫画を読みながら音楽を聴く
To listen to music while reading manga.

Before つつ

The ren'youkei of verbs can come before the conjunctive particle tsutsu つつ, which can be synonymous with nagara ながら, or can mean the continuation of an event. The latter usually appears in the pattern tsutsu aru つつある.

joukyou ga akka suru
状況が悪化する
The situation worsens.
joukyou ga akka shi tsutsu aru
状況が悪化しつつある
The situation continues worsening.
The situation keeps worsening.

The tsutsu particle is used when the verb expresses change, so you could say tsutsu is used to express how a change keeps progressing, rather than just continuing. The auxiliary ~tsuduku ～続く would be used instead if all you wanted to say was "something continues happening."

Adverbial Form

In adjectives, the ren'youkei form acts as an adverbial form, allowing adjectives to modify verbs and other adjectives.

For example, the verb naru なる, "to become," is an intransitive that must be modified by an adverb. When you say "to become" an i-adjective, it must be conjugated to ~ku ～く. When it's a na-adjective or noun, the adverbial copula ni に must be used. Observe:

kawaii
可愛い
To be cute.
kawaiku naru
可愛くなる
To become cute.

kirei da
綺麗だ
To be pretty.
kirei ni naru
綺麗になる
To become pretty.

hito da
人だ
To be a person.
hito ni naru
人になる
To become a person.

For all effects and purposes, ni に is a ren'youkei of the predicative copula da だ. So any time you would put da だ after something, and that something has to modify a verb or adjective, you put ni に instead.

hontou da
本当だ
[It] is true.
hontou ni sou da
本当にそうだ
[It] truly is that way.

hontou ni kawaii
本当に可愛い
[It] is truly cute.
hontou ni kirei da
本当に綺麗だ
[It] is truly pretty.

sugoi
すごい
[It] is incredible.
sugoku kawaii
すごく可愛い
[It] is incredibly cute.
sugoku kirei da
すごく綺麗だ
[It] is very cute.

Before 補助用言

The ren'youkei form of adjectives can come before hojo-doushi 補助動詞 and hojo-keiyoushi 補助形容詞, support verbs and adjectives, respectively, collectively called hojo-yougen 補助用言, "support expressions.".

In practice, there's really only one word that fits this criteria: aru ある, whose negative form is nai ない. To elaborate: aru is a verb, so it's a hojo-doushi, but nai is an adjective, so it's a hojo-keiyoushi. Whether that counts as two words or only counts as one you can decide yourself.

Furthermore, this function is really weird for all sorts of technical reasons.

First off, with a na-adjective, like kirei, the ren'youkei that comes before aru ある is de で.

kirei de aru
綺麗である
[It] is pretty.

The complications begin here. The modern da だ copula is a contraction of the de aru である above. Indeed, there's literally no difference in meaning between saying kirei da and kirei de aru. Similarly:

kawaiku aru
可愛くある
[It] is cute.

Has exactly the same meaning as just kawaii.

The usefulness of this extra expletive aru ある begins with its conjugation. It's possible to conjugate aru ある to its ren'youkei, ari あり, in order to use adjectives in the conjunctive form, or to use other auxiliaries that attach to the ren'youkei. For example:

kawaiku ari-tsudukeru
可愛くあり続ける
To continue being cute.

ningen de ari nagara akuma no chikara wo motsu
人間でありながら悪魔の力を持つ
In spite of being human, possesses the power of demons.
utsukushiku ari nagara doku wo motsu
美しくありながら毒を持つ
In spite of being beautiful, [it] has poison.
While beautiful, [it] is poisonous.

When the auxiliary aru ある is conjugated to the negative form, you get the negative form of i-adjectives.

kirei de nai
綺麗でない
[It] is not pretty.
kawaiku nai
可愛くない
[It] is not cute.

One interesting thing that can be done here is that the wa は particle can be inserted between the hojo-doushi and the adverbial form, marking the adjective as the topic. In general, when this happens you'll end up with a contrastive wa は.

kirei de wa aru ga, kawaiku wa nai
綺麗ではあるが可愛くはない
Pretty, [it] is but, cute, [it] isn't.
- Compare:
- kirei de aru, kawaikunai
  綺麗である、可愛くない
  Is pretty, isn't cute.
kawaiku wa aru ga, kirei de wa nai
可愛くはあるが、綺麗ではない
Cute, [it] is but, pretty, [it] isn't.

In modern Japanese, the negative of i-adjectives is generally ~kunai, while of na-adjectives it's ~dewanai. For some reason one has wa は, and the other doesn't, but they essentially come from the same process.

The word gozaimasu ございます is formal and synonymous with aru ある, while zonjimasu 存じます is synonymous with omou 思う, "to feel."

kirei de gozaimasu
綺麗でございます
[It] is pretty.
saiwai ni zonjimasu
幸いに存じます
[I] feel [it] is fortunate. (used when something would be good if you did it.)

When these two words come after the adverbial form of i-adjectives, they're affected by u-onbin.

ari-gatai
有り難い
Unlikely to have. Hard to come by.
Something you're grateful for getting.
Thank you.
ari-gataku aru
ありがたくある
(same meaning.)
ari-gataku gozaimasu
ありがたくございます
(...becomes...)
ari-gatou gozaimasu
ありがとうございます
(same meaning.)

ureshii
嬉しい
[I] am happy.
ureshiku omou
嬉しく思う
[I] feel [I] am happy.
I'm glad.
ureshuu zonjimasu
嬉しゅう存じます
(same meaning.)

Before 助動詞

The ren'youkei of verbs comes before several jodoushi.

Polite Form

The ren'youkei comes before ~masu ～ます to create the polite form. This is the reason why ren'youkei is also known as "masu stem," because it's the stem from which branches the suffix ~masu.

yomi-masu
読みます
To read. (polite.)
tabe-masu
食べます
To eat. (polite.)

The ~masu ～ます can be conjugated, but conjugating it doesn't change the ren'youkei.

yomi-mashita
読みました
To have read. (past polite.)
yomi-masen
読みません
Doesn't read. (negative polite.)
yomi-masen deshita
読みませんでした
Didn't read. (past negative polite.)

For na-adjectives, the polite jodoushi desu です is used in the affirmative. In the negative, the auxiliary aru ある is used.

kirei desu
綺麗です
[It] is pretty. (polite.)
kirei deshita
綺麗でした
[It] was pretty. (past polite.)
kirei de wa arimasen
綺麗ではありません
[It] isn't pretty.
kirei ja arimasen
綺麗じゃありません
(same meaning, contraction.)

For i-adjectives, the polite form receives desu です. The past polite is formed by the past of the i-adjective, plus desu です, not deshita でした. In the negative form, the auxiliary aru ある is used.

tadashii desu
正しいです
[It] is correct. (polite.)
tadashikatta desu
正しかったです
[It] was correct. (past polite.)
tadashiku arimasen
正しくありません
[It] isn't correct. (negative polite.)

Desiderative Form

The ren'youkei comes before ~tai ～たい to create the desiderative form.

yomi-tai
読みたい
Want to read.
tabe-tai
食べたい
Want to eat.

Once again, this can be conjugated further without affecting the ren'youkei.

tabe-takunai
食べたくない
To not want to eat.

For adjectives, the auxiliary aru ある is used.

kawaiku de ari-tai
可愛くでありたい
[I] want to be cute.
kirei de ari-tai
綺麗でありたい
[I] want to be pretty.

In general, ari-tai implies you want to continue being in a way that you already are. For example, kawaiku de ari-tai means you "want to be" kawaii, you already "be" kawaii, but in the future, you want to be, too. You want to keep that state of being.

This happens because if you weren't kawaii, and you wanted to change into being kawaii, you would use the verb naru なる, "to become," instead.

kawaiku naritai
可愛くなりたい
[I] want to become cute.

Since in ari-tai you didn't use naru, the meaning must be different from naritai, and that difference is that you already are the thing you want to be, you just want to remain that way.

Past Form

The ren'youkei comes before ~ta ～た, or ~da ～だ, to create the past form. As mentioned previously, the conjugation of the past form in godan verbs is a mess, but the meaning of the past form is exactly the same no matter how you conjugate it.

tabeta
食べた
Ate.
katta
買った
Bought.
kaita
書いた
Wrote.
oyoida
泳いだ
Swam.
koroshita
殺した
Killed.
katta
勝った
Won.
shinda
死んだ
Died.
asonda
遊んだ
Played.
yonda
読んだ
Read. (past.)
kitta
切った
Cut. (past.)

In adjectives, the ren'youkei that attaches to the ~ta jodoushi is a contraction.

As mentioned previously, de aru and ~ku aru is how na-adjectives and i-adjectives combine with the auxiliary aru. When this auxiliary is conjugated to the past form, atta あった, you get de atta であった and ~ku atta ～くあった.

The contraction of de atta is datta だった. The ~ta ～た is obviously the jodoushi. Therefore, da' だっ is the ren'youkei.

The contraction of ~ku atta is ~katta ～かった. The ~ta is the jodoushi, so ~ka' ～かっ is the ren'youkei.

kirei de atta
綺麗であった
[It] was pretty.
kirei datta
綺麗だった
(same meaning, but used normally.)

kawaiku atta
可愛くあった
[It] was cute.
kawaikatta
可愛かった
(same meaning, but used normally.)

The polite copula desu です and the polite jodoushi ~masu ～ます also have past forms.

kirei deshita
綺麗でした
[It] was pretty. (polite.)
tabemashita
食べました
Ate. (polite.)

Before ～たら

The past form plus ~ra ～ら creates the conditional form ~tara ～たら. That is, for shinda 死んだ, which suffers renjoudaku and ends in ~da ～だ, the ~tara form is shindara 死んだら. It's the same thing as the past form, plus ~ra ～ら.

tabetara
食べたら
If ate.
yondara
読んだら
If read.
kattara
勝ったら
If won.
kachimashitara
勝ちましたら
(same meaning, but polite.)
kawaikattara
可愛かったら
If were cute.
kirei dattara
綺麗だったら
If were pretty.
kirei deshitara
綺麗でしたら
(same meaning, but polite.)

Depending on the sentence, this form can translate to "if," when the consequence hasn't happened yet, or "when," when it already happened. Either way, ~tara expresses a condition that must be satisfied before the event happens, so it can also translate to "after."

benkyou shitara atama itaku naru
勉強したら頭痛くなる
After [I] study, [my] head will become painful.
If [I] study, [my] head starts hurting.
benkyou shitara atama itaku natta
勉強したら頭痛くなった
After [I] studied, [my] head became painful.
When [I] studied, [my] head started hurting.

Grammatically, ~tara is the kateikei 仮定形, "hypothetical form," of the ~ta ～た jodoushi.^{[たら - 大辞林第三版 via kotobank.jp, accessed 2019-12-12]}

Before ～たり

The past form plus ~ri ～り creates the ~tari ～たり form.

This is the ren'youkei of the jodoushi ~tsu ～つ, ~te ～て, plus the ren'youkei of the auxiliary aru ある, ari あり, ~te ari ～てあり, contracted into ~tari ～たり.^{[たり - 大辞林第三版 via kotobank.jp, accessed 2019-12-12]}

Since ari あり is ren'youkei, ~tari ～たり works like a ren'youkei, too. In particular, it's used as the conjunctive form, chaining multiple actions or events in a single sentence.

The difference between using the ren'youkei as a conjunctive form and using ~tari is that using the conjunctive form can imply you're doing or have done one thing after the other, while ~tari talks about something that's frequently done, but no in a specific order of events. For example:

watashi wa {{manga wo yondari, anime wo mittari suru} no ga suki da}
私は漫画を読んだり、アニメを見たりするのが好きだ
{The act of {reading manga, watching anime} is liked} is true about me.
I like reading manga, watching anime.

Above, manga wo yondari, anime wo mitari refer to actions that I do, but not necessarily in that order. We're also not talking about ONE time that I read manga, then watched anime. We're talking about something that I have done MANY times. About something that I usually do.

The chain of ~tari clauses is turned into a verb using the auxiliary suru する. In the sentence above, specifically, X wa NP ga suki da, the thing after ga が must be a noun, so the nominalizer no の is used after suru. Depending on the sentence these won't be necessary.

Before て

The ren'youkei also comes before ~te ～て, or ~de ～で, to form the notorious te-form. The conjugation is identical to the past form, except the vowel is ~e now. For example, since shinda 死んだ is the past form, shinde 死んで is the te-form.

By itself, the te-form can be used as an imperative.

damatte
黙って
Shut up.

It's also used to combine two verbs together, when one verb leads to the other.

sore wo mite odoroita
それを見て驚いた
Seeing that, [I] was surprised.
anime wo mite, manga wo yomi-hajimeta
アニメを見て漫画を読み始めた
Seeing the anime, [I] started reading the manga.

Chaining adjectives with the te-form results in both adjectives applying simultaneously, something is X and Y:

kawaikute kirei da
可愛くて綺麗だ
[It] is cute and is pretty.

Depending on the sentence, there may be an implication that the first adjective causes the second.

chiisakute kawaii
小さくて可愛い
[It] is small and is cute. (implying it's cute because it's small.)

For na-adjectives, things are a mess. The ren'youkei is supposed to be ni に, so you would assume that the te-form is nite にて.

But this nite にて has been contracted to de で around the 12th century.^{(Hashimoto, 1969, cited in Masuda, 2002:126)}

This is where de aru である comes from, but that, too, was later contracted to da だ.

Long story short, somehow the te-form of da だ ended up being the de で it partially originates from, at least as far as modern analyses of Japanese are concerned.

kirei de kawaii
綺麗で可愛い
[It] is pretty and is cute.

To make matters more complicated: the ~te of nite is the ren'youkei of tsu つ, and it's technically not the same thing as the ~te of te-forms, but the ~te of te-forms is said to originate in that ~te ren'youkei of tsu.^{[て - 大辞林第三版 via kotobank.jp, accessed 2019-12-14]}

Furthermore, once again, aru ある is used instead when it comes before auxiliary, e.g. de atte であって, which we'll see later.

The subordinate clause (containing the te-form), and the matrix clause (which comes after), can be related in various ways.^{(Dubinsky and Hamano, 2006:80)}

The clauses denote two distinct properties of a common subject.
The clauses denote two simultaneous or parallel events.
The subordinate immediately precedes the matrix.
The subordinate causes the matrix.
The subordinate is how the matrix is achieved.
The subordinate is the basis of judgement by which the matrix is decided.

The te-form, like the ren'youkei, is used as a conjunction, so both forms can be called conjunctive forms. And they are, indeed, extremely similar, causing much confusion regarding which one to use.

The ren'youkei can be used to list parallel events, which can be interpreted as happening in succession or related by cause-effect due to the word order. While the te-form can list parallel events, and those related by time, logic, or state.^{(益岡, 2014:5–6)}

There's a certain overlap between their functions, so, naturally, there are times when the te-form and the ren'youkei become interchangeable, both mean the same thing, and you can use either, but you must pick the one that best fits the sentence and the situation.

For example, observe the verse below:

hana wa, saite,
kotori wa naite
sono inochi owaru no sa
花は咲いて
小鳥は啼いて
その命終わるのさ
The flower blooms,
the small-bird sings,
that life ends, [you'll see].
- —森昌子孤愁人（1986-06-29） - on youtube.

In the verse above, the verbs saku 咲く, "to bloom," and naku 啼く, "(for an animal) to sing," are in the te-form, saite, naite. The question is: why can't you just use the ren'youkei instead?

hana wa saki,
kotori wa naki,
sono inochi owaru no sa
花は咲き、小鳥は啼き、その生命終わるのさ
The flower blooms, the small-bird sings, that life ends, [you'll see].

You could do that, but then the three events—the flowers blooming, the small-birds singing, that life ending—become isolated from each other.

Since the te-form wasn't used, that's not the case, so we can imagine a temporal order exists: the flowers bloomed, then the birds sung, then that life ends.

What life are we talking about? I have no idea. It's probably a verse about the ephemerality of life. It could be that birds singing and flowers blooming represent the passage of time. Or it could be that their life ultimately ends after they do what they normally do. Who knows? It doesn't matter.

Another example, from the same song:

ai wa, kaze sa,
hageshiku fuite
doko ka e kieru yo
愛は風さ
激しく吹いて
何処かへ消えるよ
Love, [it] is wind, you see,
[it] blows intensely,
disappearing to somewhere.
- fuku
  吹く
  To blow (air).
ai wa, kaze sa,
kizu-ato nokoshi
doko ka e satta yo
愛は風さ
傷跡残し
何処かへ去ったよ
Love, [it] is wind, you see,
it left scars,
and left to somewhere.
- nokosu
  残す
  To leave (something remaining).
- saru
  去る
  To leave (a place). To exit. To go away.
- Note: in the video linked previously, it's singed yoake ni satta yo 夜明けに去ったよ, "left at the morning." The lyrics of the song, and on the video, are doko ka e satta yo.

In the first verse above, the te-form is used because love disappeared like wind, blowing away, so the verb "to blow" acts as an adverb modifying "to disappear." How does love disappear? By blowing away.

In the second verse, the ren'youkei is used, because the two events happened in isolation. First, love left scars, then, it went away somewhere. Leaving scars didn't cause it to go away. And the sentence doesn't imply it left scars as it went away.

But that could be the case, right? Leaving scars, the love went away. Why not use nokoshite 残して here instead?

Again, absolutely no idea. Maybe because this is a song, and the song-writer wanted the number of mora to match: ha-ge-shi-ku fu-i-te はげしくふいて, seven mora, ki-zu-a-to no-ko-shi きずあとのこし, seven mora, too.

Trying to figure out why someone would one word over the other when the two words mean the same thing seems pretty pointless. For example, can you explain why I used "pretty" instead of "very"? Because I can't. I just used. Could've said "very" pointless, but didn't.

When interchangeable, the te-form emphasizes that one event happens IMMEDIATELY after the other, and it's preferred in spoken language, while the ren'youkei is preferred in written language, in narration.^{(生越, 1988:64)}

This means that, in manga, if a character is talking about something that happened to them yesterday, they'll use the te-form, but if they're reading out loud a report in a boardroom, they'll be using more ren'youkei.

The te-form of verbs can also comes before hojo-yougen, "support expressions." There are many of them.

yonde-hoshii
読んでほしい
[I] want [you] to read [it] for [me].
yonde-ageru
読んであげる
[I] will read [it] for [you].
yonde-kureru
読んでくれる
[He] reads [it] for [me].
yonde-oku
読んでおく
To read [it] just in case. (in preparation for something that may happen later.)

The most well-known hojo-yougen is the auxiliary verb iru いる.

yonde-iru
読んでいる
To be reading.

Although it translates to "~ing" in some verbs, the progressive form, in others it translates to "~ed," which is the perfect form. This happens with ergative verb pairs. For example:

yaite-iru
焼いている
To be burning [something].
To be cooking [something].
To be baking [something].
- yaku
  焼く
  To burn [something]. (transitive.)
yakete-iru
焼けている
To be burned.
To be cooked.
To be baked.
- yakeru
  焼ける
  To burn. (intransitive.)

In spite of the "~ing" translation, whenever ~iru appears, the main verb has already occurred. For example, yaite-iru means you've burned something already, and yonde-iru means you've read something already.

This means that shinde-iru 死んでいる can't mean "to be dying," because someone who is "dying" in English hasn't died already. Instead, shinde-iru means "to be dead," and shini-kakete-iru 死にかけている means "to be dying," or to be in a state close to dying.

With verbs, the hojo-doushi aru ある works different from how it works with adjectives.

yonde-aru
読んである
(For a book) to have been read.
yonde-nai
読んでない
(For a book) to not have been read.

In essence, ~aru and ~nai are the passive of ~iru. The subject becomes the patient with them.

These are also called te-iru form, te-aru form, te-oku form, and so on.

With i-adjectives and na-adjectives, aru ある is used before such auxiliaries. This works just like ari-tai, the auxiliary modifies the state of being.

kirei de atte hoshii
綺麗であってほしい
[I] want [you] to be pretty.
kawaiku atte hoshii
可愛くあってほしい
[I] want [you] to be cute.

The te-form can also be used before the wa は particle to describe an action. In most cases, it's used with negative words, like dame ダメ, "no good," ikenai いけない, "can't go," naranai ならない, "can't be," which all mean the same thing in practice: something mustn't be done.

kibou ga atte wa naranai
希望があってはならない
[You] must not have hope.
kirei de atte wa naranai
綺麗であってはならない
[It] must not be pretty.
kawaiku atte wa naranai
可愛くあってはならない
[It] must not be cute.
yonde wa naranai
読んではない
[You] must not be read [it].
shitte wa naranai
知ってはならない
[You] must not learn [it].

Note: i-adjectives must be conjugated to ~ku atte ～くあって, which has the te-form of aru ある, however, nai ない, being the negative form of aru ある, doesn't need aru ある after it, and the wa は comes right after the nakute なくて.

kibou ga nakute wa naranai
希望がなくてはならない
[You] must not not have hope.
[You] must have hope.
kirei de nakute wa naranai
綺麗でなくてはならない
[It] must not not be pretty.
[It] must be pretty.
kawaikunakute wa naranai
可愛くなくてはならない
[It] must not not be cute.
[It] must be cute.
yomanakute wa naranai
読まなくてはならない
[You] must not not read [it].
[You] must read [it].
shiranakute wa naranai
知らなくてはならない
[You] must not not learn [it].
[You] must learn [it].

Before やがる

The ren'youkei also comes before the jodoushi ~yagaru ～やがる. It translates roughly to "having the nerve to do something," "daring to do something," and so on.

ano yarou, nige-yagatta!
あの野郎、逃げやがった！
That bastard, [he] ran away!