LESSON NOTES · レッスンノート

Akihabara & otaku Japan · Sep 17, 2026

Otaku slang in Japanese: し, とうとい, ぬま and the words fandom actually runs on

し (the one you support), とうとい (roughly "precious beyond words"), ぬま (a swamp you cannot climb out of) and 供給きょうきゅう (new official material) are the four words that unlock most Japanese fan conversation. They are ordinary words repurposed, which is why a dictionary will not help you much.

This is the layer of Japanese that sits between textbook vocabulary and genuinely understanding a Japanese fan community. Every word below has a plain meaning you may already know, and a fandom meaning that has drifted a long way from it.

The basics

し: the one you support

す (おす) means "to push" or "to recommend." し is the noun form, and it means the member, character or performer you actively back.

しはだれですか。 — Who's your favourite? (casual, a completely standard question) しがとうとい。 — My favourite is precious. (casual, the most common two-word sentence in Japanese fandom)

The related verb is す, used directly: わたしはこのキャラをしています ("I'm backing this character"). You will also meet:

  • かつ (おしかつ) — the activity of supporting your し: going to events, buying goods, travelling
  • single / はこ (はこおし) — backing one member versus backing the whole group
  • どうたん (どうたん) — someone whose し is the same as yours
  • どうたん拒否きょひ (どうたんきょひ) — refusing to associate with people who share your

That last one is real, and understanding it prevents a genuinely awkward moment. Some fans treat their し as a private relationship and find shared enthusiasm uncomfortable rather than bonding.

とうとい: precious, beyond expression

とうとい (とうとい) is a real, old word meaning "noble, sacred, precious" — the kind of thing used about shrines and human life. Fandom borrowed it wholesale, and it now functions as an exclamation when something is so good you cannot analyse it.

とうとい……(no useful translation — "I cannot cope with how good this is")

It is not used about plot quality or animation. It is used about a moment: two characters standing near each other, a facial expression, a line delivery. If you could explain why, you would not say とうとい.

ぬま: the swamp

ぬま (ぬま) means a marsh or bog. In fandom it means a series or franchise you have fallen into and cannot get out of.

完全かんぜんぬまです。 — I'm completely sunk. (casual — said with affection, not regret) ぬまにはまりました。 — I fell into the swamp. (casual, announcing a new obsession)

はまる is the verb that goes with it — it means "to fit into" or "to get stuck in," and by itself it already means "to get hooked on something." ぬま just makes the hole deeper.

Beyond the basics

供給きょうきゅう and 燃料ねんりょう: official material as a resource

供給きょうきゅう (きょうきゅう) is a plain economics word meaning "supply." Fans use it for new official content — an episode, an announcement, an official illustration, a merchandise line.

供給きょうきゅうおおすぎる。 — There's too much new material. (casual — a complaint that is not a complaint) 供給きょうきゅうがない。 — There's nothing new. (casual — a genuine complaint)

燃料ねんりょう (ねんりょう, "fuel") does a similar job with more heat: 燃料ねんりょう投下とうか ("fuel dropped") describes an official release that sets a fandom on fire for a week.

かみかい and かみ: divine episodes

かみ (かみ) means god, and as a prefix it means "outstanding."

  • かみかい (かみかい) — a god-tier episode
  • 神曲しんきょく (かみきょく) — an outstanding song
  • かみ対応たいおう (かみたいおう) — an exceptionally gracious response, usually from a performer to a fan

今週こんしゅうかみかいでした。 — This week's episode was incredible. (polite-casual, everyday fan talk)

かみ対応たいおう is worth knowing because it appears well outside fandom — a shop or a company can be praised for かみ対応たいおう when their customer service goes far beyond expectation.

履修りしゅう: studying a series

履修りしゅう (りしゅう) is the word for registering for a university course. Fans use it for working through a series they have not seen.

まだ履修りしゅうしてません。 — I haven't studied up on it yet. (casual, said about a show everyone else has watched)

The joke inside the word is that consuming media is framed as coursework — which, in a fandom with decades of back catalogue, it genuinely resembles. The related 布教ふきょう (ふきょう, "missionary work") means pushing a series onto your friends.

布教活動ふきょうかつどうしてます。 — I'm out evangelizing. (casual, about getting friends into something)

エモい: the feeling with no name

エモい comes from English "emotional" and is wasei-eigo in its purest form — the English word does not mean this.

なんかエモい。 — It's got a feeling to it. (casual — nostalgic, moving, slightly melancholy, all at once)

It describes a mood, usually nostalgic and slightly wistful: an empty classroom at sunset, an old song, a train platform at night. It sits close to なつかしい (nostalgic) but with more aesthetic weight.

解釈かいしゃくちがい: reading it differently

解釈かいしゃく (かいしゃく) means "interpretation," and 解釈かいしゃくちがい means someone's reading of a character conflicts with yours.

解釈かいしゃくちがいです。 — That's not how I read that character. (casual, and a real disagreement)

This is more serious than it sounds. In Japanese fandom, 解釈かいしゃくちがい is a genuine reason to stop following someone, and stating it is a clear signal you want distance rather than debate.

The physical-goods vocabulary

Japanese Reading Meaning
グッズ ぐっず Merchandise
つうバッグ いたばっぐ A bag covered in badges of your
かんバッジ かんばっじ Pin badge
アクスタ あくすた Acrylic stand figure
限定げんてい げんてい Limited edition
完売かんばい かんばい Sold out
つむ To stack up unplayed games or unread books
課金かきん かきん Spending money in a game
特典とくてん とくてん Bonus item that comes with a purchase

つうバッグ takes its つう (pain) from つうくるま — a car covered in anime decals, so garish it "hurts" to look at. The word is self-deprecating and entirely affectionate.

む gives みゲー (a stack of unplayed games) and どく (つんどく, a stack of unread books) — the latter is an old word that predates gaming by a century. For buying any of this in person, see ten phrases that make shopping in Akihabara easier.

Common mistakes

  • Using とうとい about quality. It is not "this is well made." It is an expression of being overwhelmed. Say かみかい for quality.
  • Translating し as "favourite." Close, but し carries active support — buying, attending, promoting. A favourite is passive.
  • Assuming どうたん is friendly. どうたん拒否きょひ exists. Not everyone wants to meet someone who shares their し.
  • Using エモい for straightforward happiness. It needs a wistful edge. A birthday party is たのしい; an old photo of that party is エモい.
  • Saying 解釈かいしゃくちがい casually. It signals a real rift, not a light difference of opinion.
  • Using 課金かきん outside games. It specifically means putting money into a game or app, not general spending.
  • Reading とうとい as そんとい. It is とうとい. とうとい and たっとい are both valid readings of the kanji, but fandom says とうとい.

The core set, at a glance

Japanese Reading Literal In fandom
おし Something pushed The one you support
とうと とうとい Noble, sacred Overwhelmingly precious
ぬま ぬま Swamp An obsession you cannot leave
供給きょうきゅう きょうきゅう Supply New official material
かみかい かみかい God episode An outstanding episode
履修りしゅう りしゅう Course registration Working through a series
布教ふきょう ふきょう Missionary work Recommending aggressively
エモい えもい (from "emotional") Nostalgic, wistful, moving
解釈かいしゃくちが かいしゃくちがい Interpretation gap An incompatible reading
つむ To stack To accumulate unfinished media

Practice

Questions 1 and 2 are the pair worth separating: overwhelmed versus impressed.

1. Two characters share a quiet moment and you cannot articulate why it destroyed you. What do you say?

Show answer

とうとい…… — Used when you cannot explain why. If you can explain it, this is the wrong word.

2. This week's episode was outstandingly well made. What do you say?

Show answer

今週こんしゅうかみかいでした。かみ as a prefix means "outstanding." This is about quality, not about being overwhelmed.

3. Ask someone who their し is.

Show answer

しはだれですか。 — Completely standard. し implies active support, not just a preference.

4. Announce that you have fallen into a new obsession.

Show answer

ぬまにはまりました。ぬま is a swamp; はまる is to get stuck in it. Said with affection.

5. Say there has been too much new official material lately.

Show answer

供給きょうきゅうおおすぎる。供給きょうきゅう is literally "supply." This is a complaint that is not a complaint.

6. Admit you have not watched a series everyone else has.

Show answer

まだ履修りしゅうしてません。履修りしゅう is course registration. Watching is framed as coursework.

7. Say you have been pushing a series onto your friends.

Show answer

布教活動ふきょうかつどうしてます。布教ふきょう is missionary work. The joke is fully intended.

8. Describe an old photo of a school classroom at sunset.

Show answer

なんかエモい。 — Nostalgic with a wistful edge. たのしい would be wrong: this is not fun, it is a feeling.

9. What does どうたん拒否きょひ mean, and why does it matter?

Show answer

おなしのひとかかわりたくない、という立場たちば — Some fans treat their し as private. Assuming shared enthusiasm is bonding can be a real misstep.

10. What does みゲー mean, and what older word is it built on?

Show answer

ったのにあそんでいないゲームのやまどくからています。む means to stack. どく (unread books) is a century older than gaming.

FAQ

Is this slang safe to use with Japanese fans? Yes — all of it is current, ordinary fan vocabulary, not edgy or offensive. The only one to handle carefully is 解釈かいしゃくちがい, which is a real statement of disagreement.

Is し only used for idols? No. It works for anime characters, voice actors, athletes, VTubers, wrestlers and increasingly for non-people — しのカフェ (a café you champion) is normal usage now.

Where does とうとい come from? It is a genuinely old word, used in religious and formal contexts for centuries. The fandom usage emerged in the 2010s, and the contrast between the solemn original and the flailing modern use is part of the joke.

What is the difference between オタク and かつ? オタク is an identity; かつ is an activity. You can do かつ without calling yourself オタク, and the newer word carries much less of the negative weight オタク historically had.

Does 課金かきん mean any purchase? No. It specifically means putting money into a game or app, usually free-to-play. Buying a physical item is う, not 課金かきん.

Is つうバッグ an insult? Not at all. The つう comes from つうくるま and the whole word is affectionately self-mocking. People make them deliberately and show them off.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

推し	おし — the one you support
推す	おす — to push, to back
推し活	おしかつ — fan activity supporting your favourite
尊い	とうとい — precious, sacred; overwhelmingly good
沼	ぬま — swamp; an obsession you cannot leave
はまる	はまる — to get stuck in, to get hooked
供給	きょうきゅう — supply; new official material
燃料	ねんりょう — fuel
神回	かみかい — an outstanding episode
神対応	かみたいおう — exceptionally gracious response
履修	りしゅう — course registration; working through a series
布教	ふきょう — missionary work; recommending
解釈	かいしゃく — interpretation
限定	げんてい — limited edition
完売	かんばい — sold out
特典	とくてん — bonus item
課金	かきん — spending money in a game
積む	つむ — to stack up

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime. Students usually arrive with し already — they picked it up from subtitles — and then discover that とうとい, ぬま and 供給きょうきゅう are the three that actually make fan conversation land.

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Sources: the author's own lessons and standard reference grammars.

More drills like the ones above, plus a timed JLPT-style mock test: Practice

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