Heterochromia

In anime, some characters have eyes of different colors. The technical term for that in English is heterochromia, specifically, heterochromia iridis, which is having irises of different colors.

In Japanese, the term for heterochromia in general is its katakanization, heterokuromia ヘテロクロミア. The common term for heterochromatic eyes in anime characters is oddo-ai オッドアイ, "odd eyes."

Character: Todoroki Shouto 轟焦凍
Anime: Boku no Hero Academia, 僕のヒーローアカデミア (Episode 23)

• In Japanese
• Examples
  
  • Siblings
  • Cats
    
    • 金目銀目
  • Complex
  • Prosthetic
  • Transplant
  • Blindness
  • Magic Eyes
  • Contact Lens
• List of Characters

In Japanese

The word "heterochromia" in Japanese is ishokushou 異色症, or its katakanization, heterokuromia ヘテロクロミア.

In both languages heterochromia commonly refers to the having eyes of different colors, but other kinds of heterochromia also exist, like having different colors of hair or skin.

• Todoroki Shouto has both eye and hair heterochromia.

The technical term for heterochromatic irises in Japanese is kousai-ishoku-shou 虹彩異色症. Literally:

• kousai
  虹彩
  Iris.
• i~
  異
  Different. (like in isekai 異世界, "different world.")
• shoku
  色
  Color.
• shou
  症
  Condition. (medical.)

A common term for it is just oddo-ai オッドアイ, "odd-eyes." This term is made-up English, wasei eigo 和製英語, which means "odd eyes" doesn't mean heterochromia in English-speaking countries, but it does mean heterochromia in Japan.

For the record: an "odd-eyed cat" is a cat with heterochromia in English, but you don't call people odd-eyed. Similarly, oddo-ai is often used toward animals, and you may want to refrain from using it toward real people.

Another wasei-eigo, bai-ai バイアイ, "bi-eyes." also refers heterochromia.

Another way to describe it would be:

• ishoku hitomi
  異色瞳
  Different-color iris.

Examples

For reference, some examples of characters with heterochromatic eyes.

Character: Mikuni 美邦
Anime: Shangri-La, シャングリ・ラ (Episode 5)

Oskar von Reuenthal オスカー・フォン・ロイエンタール
Anime: Legend of the Galactic Heroes, Ginga Eiyuu Densetsu 銀河英雄伝説 (Episode 53)

• kingin youdou
  金銀妖瞳
  Gold-silver bewitching irises.
  • In the anime, this term, sometimes translated as "bewitching eyes," refers to Reuenthal's eyes.

Character: Juugo ジューゴ
Anime: Nanbaka ナンバカ (Episode 1)

Anime: Sousei no Aquarion, 創聖のアクエリオン (Episode 1)

• tagan
  多眼
  Having more than two eyes.

Siblings

Some characters who are siblings both have heterochromatic eyes.

Left: Suiseiseki 翠星石
Right: Souseiseki 蒼星石
Anime: Rozen Maiden, ローゼンメイデン (Episode 9)

Left: Aura Bella Fiora アウラ・ベラ・フィオーラ
Right: Mare Bello Fiore マーレ・ベロ・フィオーレ
Anime: Overlord, オーバーロード (Episode 1)

Cats

Heterochromia is more common cats than in humans. Consequently, there are also cat girl characters that have eyes of different colors.

Character: Neko ネコ
Anime: K (Episode 4)

金目銀目

The term kin-me-gin-me 金目銀目, "gold eye, silver eye," refers to cats that have one yellow eye and one blue eye.

Character: Molly モリィ
Anime: Mahoutsukai no Yome 魔法使いの嫁 (Episode 4)

Character: Coconut ココナツ
Anime: Nekopara ネコぱら (Episode 1)

Character: Ibaraki-douji 茨木童子
Anime: Onigiri 鬼斬 (Episode 3)

Here's an example with a dog, or rather, a fox:

Character: Miketsukami Soushi 御狐神双熾
Anime: Inu x Boku SS, 妖狐×僕ＳＳ (OVA, Stitch)

Complex

Some characters that have heterochromatic eyes already have some very peculiar, colorful eye designs to begin with.

Character: Lucoa ルコア
Anime: Kobayashi-san Chi no Maidragon, 小林さんちのメイドラゴン (Episode 3)

Character: Tet テト
Anime: No Game No Life, ノーゲーム・ノーライフ (Episode 1)

Prosthetic

Characters that have one prosthetic eye normally choose a color that matches their other eye, but there are also cases of characters that have a prosthetic eye of different color.

Character: Asama Tomo 浅間智
Anime: Kyoukaisenjou no Horizon, 境界線上のホライゾン (Episode 1)

• gigan
  義眼
  Artificial eye. Prosthetic eye.

Character: Daniel Dickens ダニエル・ディケンズ
Anime: Angels of Death, Satsuriku no Tenshi 殺戮の天使 (Episode 1)

• Heterochromatic double-pupils artificial eyes. Because why not.

Transplant

Sometimes, characters have eyes of different colors because they got the second eye from someone else. Typically this is implied from the fact they're covered in stitches, rather than the audience being explicit told about or shown the transplantation.

Character: Hatori Chise 羽鳥智世
Anime: Mahoutsukai no Yome 魔法使いの嫁 (Episode 22)

Character: Zombina ゾンビーナ
Anime: Monster Musume no Iru Nichijou: Hobo Mainichi ____! Namappoi Douga, 「モンスター娘のいる日常」ほぼ毎日○○！生っぽい動画 (ONA)

• ishoku
  移植
  Transplantation.

Character: Mahito 真人
Anime: Jujutsu Kaisen 呪術廻戦 (Episode 7)

Blindness

Blind eyes are normally rendered in lighter colors than healthy eyes. Consequently, a character who has gone blind in one eye may end up with different-colored eyes, even if he wasn't born with heterochromia.

Character: Ren Hakuryuu 練白龍
Anime: Magi: The Labyrinth of Magic, マギ (Episode 5)

• shitsumei
  失明
  Losing eyesight.

Magic Eyes

Some characters have different colored eyes not because they were born with heterochromia, but because they've acquired some sort of ability or curse that manifests in the eye.

Character: Lelouch Lamperouge ルルーシュ・ランペルージ
Anime: Code Geass: Hangyaku no Lelouch, コードギアス 反逆のルルーシュ (Episode 3)

• Lelouch's left eye temporarily changes color when he activates his ability.

Some of such eyes are called magan 魔眼, "magic eye," or jagan 邪眼, "evil eye," specially if staring at people does them harm or something like that. The term also refer to eyes that can see things normal people can't see.

Character: Sariel サリエル
Anime: Nanatsu no Bitoku 七つの美徳 (Episode 7)

• Sariel's right eye is a jagan that brings upon destruction when activated.

Characters with permanent magic eyes often wear an "eye-patch," gantai 眼帯, to hide it from the public.

Character: Ciel Phantomhive シエル・ファントムハイヴ
Anime: Black Butler, Kuroshitsuji 黒執事 (Episode 20)

• The pentagram in Ciel's right eye is proof of his contract with a demon.

Character: Hatake Kakashi はたけカカシ
Anime: Gekijouban Naruto: Dai Koufun! Mikazuki-jima no Animaru Panikku Datte ba yo!, 劇場版 NARUTO -ナルト- 大興奮！みかづき島のアニマル騒動だってばよ (Movie)

• sharingan
  写輪眼
  Copy-wheel eye. In the Naruto, a wheel-shaped eye capable of copying abilities.

Character: Ghislaine Dedoldia ギレーヌ・デドルディア
Anime: Mushoku Tensei: Isekai Ittara Honki Dasu 無職転生 ～異世界行ったら本気だす～ (Episode 8)

• Context: apparently capable of viewing mana (magic).

Character: Kaneki Ken 金木研
Anime: Tokyo Ghoul, Toukyou Guuru 東京喰種-トーキョーグール (Episode 1)

• sekigan
  隻眼
  Having only one eye instead of both.
• In Tokyo Ghoul, ghouls' eyes turn black, but Kaneki, who is half-human, half-ghoul, only has one ghoul eye.

Contact Lens

Influenced by such characters, chuunibyou 中二病 characters also wear eye-patches and pretend to have magic eyes.

Character: Takanashi Rikka 小鳥遊六花
Anime: Chuunibyou demo Koi ga Shitai! 中二病でも恋がしたい！ (Episode 1)

• karaa kontakuto
  カラーコンタクト
  Colored contacts.

Character: Hanazono Yurine 花園ゆりね
Anime: Jashin-chan Dropkick, 邪神ちゃんドロップキック (Episode 12, OVA)

• Context: she's actually shown in a previous episode without the eye patch after leaving bath without colored contacts, so I was rather surprised that she did have a contact on in this episode.

Character: Hasegawa Kobato 羽瀬川小鳩
Anime: Boku wa Tomodachi ga Sukunai 僕は友達が少ない (Episode 3)

• Context: Kobato drinks "blood," also known as tomato juice.

List of Characters

For a more complete list of characters with heterochromia, see the following websites:

• オッドアイ - dic.nicovideo.jp, accessed 2020-02-08.
  • In Japanese, contains the colors of each eye, includes characters from manga.
• Tag: heterochromatic eyes - anidb.net, accessed 2020-02-08.
  • In English, only anime characters.