-suru ga ii ～するがいい

In Japanese, suru ga ii するがいい, or any verb plus ga ii, means literally "it's better to do [something]."

In anime, however, it's pretty much always used by evil-looking characters who're full of themselves to pretentiously tell someone "do this, I allow you to do," a permission, or "it's better you do so," which sounds like an order.

In either case, ga ii is often not translated to English at all.

Manga: Gabriel DropOut, Gavuriiru Doroppuauto ガヴリールドロップアウト (Chapter 3)

• Explanation
• Examples
  
  • 恐怖するがいい
  • 蒸発するがいい
  • 吸い込むがいい
  • 見るが好い
  • 哀願してくるがいい

Explanation

The reason why suru ga ii can sound like either a permission or an order to do something comes from the fact that the i-adjective ii いい means literally "good."

• suru ga ii
  するがいい
  To do is good.

It means a permission because it's the answer to the following question:

• To do is bad?
• No.
• To do is good. (you're allowed to do it, it's okay.)

And it sounds like an order because of its opposite:

• To do is good.
• Therefore:
• To not do is bad. (you don't want to not do it.)
• There'll be consequences.
• Do it... or else!!!

In this latter case, since not doing it is bad, doing it is "better" than not doing it. That is: "you better do it."

Note however, that suru ga ii isn't normal Japanese, it's evil anime character Japanese. For reference, let's see a verb with ga ii compared to more normal ways to say that "verb is good:"

• miru ga ii
  見るがいい
  To look is good.
  It's better you look. (or else!!)
  I allow you to look. (and you should.)
  Look. (what else needs to be said?)
• miru to ii
  見るといい
  If look: good.
  It's good if you look. (not telling you that you should, but it's good if it happens.)
• mireba ii
  見ればいい
  If look: good.
  It's good if you look. (and maybe you should, because, why haven't you looked yet?)
• mitara ii
  見たらいい
  If looked: good.
  It's better if you looked. (that could also not happen, though.)
• mita hou ga ii
  見た方がいい
  The way [in which you] look is good.
  It'd be better if you looked. (this is an advice.)

And there's other ways to tell someone to do something as an order, a command:

• miro
  見ろ
  See.
  • Imperative form.
• minasai
  見なさい
  See.
  • nasai form, tends to be used by female characters instead.
• mite
  見て
  See.
  • te-form. Doesn't sound as assertive as the forms above.

Grammar

In modern Japanese grammar, suru ga ii するがいい sounds kind of wrong. That's because normally you can't use a case marking particle, such as ga が, right in front of a verb, or clause. It must go after a noun.

See above how suru hou ga ii has the noun hou between suru and ga. The verb suru, and whatever comes before suru, becomes a relative clause for noun hou:

• The way [in which you] do [it] is good.
• ...hou ga ii
  ～方がいい
  The way... is good.

If we were to use the most generic nominalizer Japanese has to offer, we'd end up with this:

• suru no ga ii
  するのがいい
  Doing is good.

Which is a much more normal phrase and doesn't have the evil-sounding nuance of suru ga ii.

To explain why this happens first we need to get why suru ga ii is used even though grammatically it doesn't fit.

It's old Japanese. It's an old way of saying. From older times. When it made more sense grammatically. Nevertheless it's still used today, specially in period pieces and anime.

More technically, although in modern Japanese suru ga ii looks like it's the dictionary form of the verb, or its predicative form, shuushikei 終止形, plus ga ii, in old Japanese the verb would be in the rentaikei 連体形, attributive form.

And this attributive form was allowed to be treated like a noun, which is why it could be marked as the subject by ga が.^{[<動詞の辞書形>　+　がよい ―　How is this allowed? - japanese.stackexchange.com, accessed 2019-08-06]}

Note that, also in the same old Japanese, the word yoi よい was used instead of ii いい. For example:

• hanasu ga yoi
  話すがよい
  To speak is good.
  • You may speak.
  • I allow you to speak.
  • I allow thee to speak.
• saru ga yoi
  去るがよい
  To leave is good.
  • You may leave.
• suru ga yoi
  するがよい
  To do is good.
• shinu ga yoi
  死ぬがよい
  To die is good.
  • It's better if you die.
  • You've disgraced your honor.
  • Your ancestors.
  • Shame on u.
  • Commit sūdoku 数独.
• korosu ga yoi
  殺すがよい
  To kill is good.
  • You may kill him.
  • In fact, KILL HIM, KILL THAT DUDE!!!

So now we have the two components needed to understand why suru ga ii is used by evil-looking villains in anime.

First off, it's because, being either permission or order, it ends up sounding like both. So the evil guy sounds like he's doing a favor, being a benevolent superior being, allowing good stuff to happen, even though in practice he's pretentiously ordering stuff.

The second reason is because it comes from old times. This is just like how the word kisama 貴様 isn't used in modern Japanese, but you see it in anime all the time anyway.

If the character is anachronistic, a time-travelling feudal lord, or maybe the anime is actually set in the past, in a samurai era, then they'll naturally use it. If it's not anachronistic, then they're just mimicking the nobles of the time, or may he's a chuuni who has seen too many samurai anime and is trying to sound cool.

Examples

For reference, some examples of evil characters using suru ga ii and verb ga ii in manga.

恐怖するがいい

Let's start with the evilest one.

Manga: Gabriel DropOut, Gavuriiru Doroppuauto ガヴリールドロップアウト (Chapter 3)

• ahahaha'
  アハハハっ
  *evil demon maniac laugh*
• watashi wa jigoku no shihaisha ni naru mono
  私は地獄の支配者になるもの
  I'm the person [who] will become the ruler of Hell.
• Kurumizawa Satanikia Makudoweru
  胡桃沢=サタニキア=マクドウェル
  Kurumizawa Satanichia McDowell.
  • = is used to separate katakana words in names sometimes, just like the middle dot ・.
• kono yo no ashiki koto wa
  watashi no tame ni aru'!!
  この世の悪しきことは私のためにあるっ！！
  The evil things of this world exist [just] for me!!
• ningen-domo!!
  人間ども！！
  Humans!!
  • domo is a pluralizing suffix that implies inferiority, being humble toward oneself but derogatory toward others. (in this case, the demon girl thinks humans are inferior to her.)
  • It's like saying "you lot" in a bad way, for example.
• watashi ni ononoki
  kyoufu suru ga ii!!
  私におののき恐怖するがいい！！
  [Shiver in fear before me!!]
  • Literally: to tremble and fear me is good.
  • ononoku 慄く
    To tremble. To shake. (in fear.)

蒸発するがいい

Manga: Houshin Engi 封神演義 (Chapter 2)

• Context: evil guy attacks Taikoubou, the main character.
• iwa wo mo tokasu honoo de
  jouhatsu suru ga ii!!
  岩をも融かす炎で蒸発するがいい！！
  With this flame [that] even melts boulders, evaporate!!
• Taikoubou!!!
  太公望！！！
  (character name.)

吸い込むがいい

Manga: Houshin Engi 封神演義 (Chapter 4)

• Context: all according to the keikaku.
• sou
  そう
  [That's right.]
• dokuka no kona yo!!
  毒蛾の粉よ！！
  [It's] poisonous moth powder.
• saa
  さあ
  [Come on.]
• karada ga
  kusare-ochiru made
  haifu no oku ni
  sui-komu ga ii!!
  体が腐れ落ちるまで配布の奥に吸い込むがいい！！
  Until [your] body rots and drops,
  breathe [it] into the depths of [your] lungs!!

見るが好い

Sometimes ii いい is spelled with kanji as ii 好い instead.

Book: "The Three Treasures," Mittsu no Takara 三つの宝 (Page 148)
Author: Akutagawa Ryūnosuke 芥川龍之介
Published: Year 3 of the Shouwa 昭和 era, a.k.a. 1922. (see years and eras.)
Source of the image: 三つの宝 - 国立国会図書館デジタルコレクション - dl.ndl.go.jp, accessed 2019-03-22.
The book in plain text, slightly different: 三つの宝 芥川龍之介 - www.aozora.gr.jp, 2019-03-22.

• ou (aza-warafu.) namaiki na! watashi no mantoru no chikara wo miru ga ii.
  王　（嘲笑ふ。）生意気な！　わたしのマントルの力を見るが好い。
  King: (sneers.) naive, [aren't you]! [You shall] see the power of my mantle!
  • warafu 笑ふ
    Ancient pronunciation of warau 笑う, found in "classical literature," kobun 古文. This book isn't all that ancient, though, so it's probably just this character, a "king," that speaks in this ancient way.
  • See also: Why is ha は pronounced wa? Particles he へ as e, wo を as o?
  • Parentheses can surround actions in stories. Just like asterisks in English: *sneers.*
  • See also: （笑）

哀願してくるがいい

An important reminder that not every time suru ga ii is used it's by an evil demon doing evil things. Sometimes it's just an awfully pretentious character who's full of pride and looks down at other people.

Manga: Kaguya-sama wa Kokurasetai ~Tensai-Tachi no Ren'ai Zunousen~ かぐや様は告らせたい～天才たちの恋愛頭脳戦～ (Chapter 1)

• kuku...
  くく･･･
  *chuckle*
• sassato さっさと
  Already.
  • As in: do the following thing already.
  • Hurry up and...
• sono
  kanpeki-na ojousama no
  kamen wo kuzushi
  その完璧なお嬢様の仮面を崩し
  Destroy that mask of perfect rich girl.
  • ojousama お嬢様
    Daughter.
    Rich girl. (daughter of a rich family.)
  • kuzusu 崩す
    Destroy. (by crumbling, falling apart. Not with a hammer or something.)
  • i.e. ruin the facade of being a perfect girl, stop putting on appearances, etc.
• sekimen shi-nagara
  ore ni aigan shite
  kuru ga ii.
  赤面しながら俺に哀願してくるがいい
  While blushing, come supplicate me.
  • TL note: supplicate means beg.
  • sekimen 赤面
    Red face. (literally.)
    Blushing.
  • shi-nagara しながら
    While doing. (the verb suru plus nagara.)
  • shite-kuru してくる
    Come do. (the verb suru plus the auxiliary verb kuru.)
• kaichou...
  会長･･･
  [Student] council president...
• oshitai moushi agete orimasu......
  おしたい申し上げております･･････
  [I luv u.]
  • No, really.
  • This is a confession spoken in some polite keigo.
  • oshitai moushi agete orimasu
    お慕い申し上げております
    [I'm] saying to you: [I] love [you].
  • o- お～
    Polite prefix.
  • shitau 慕う
    To yearn for [someone]. To adore. To love dearly.
  • mousu 申す
    To say.
  • ageru あげる
    [To do] for [someone].
    [To do] to [someone].
    (auxiliary verb.)
  • oru おる
    To be.
  • -masu ～ます
    Polite suffix.

Further Reading

References

• 「したまえ」と「しなさい」と「するがよい」について - oshiete.goo.ne.jp, accessed 2019-03-01.
• がいいの類語, accessed 2019-03-01.