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Japanese Slang About Boobs: From Flat to Humongous

Welcome to your first Japanese class at MAL High School! Today, we're learning all about Japanese netspeak. Specifically, boob-related slang! Don't pretend you're not curious. How many of these do you already know?

by RilakkuLina
Mar 17, 12:47 AM | 20,130 views

We've probably all picked up a couple phrases of Japanese through watching anime. It's certainly how I started learning! If you're in search of more Japanese phrases you'll never use in real life, you're in the right place, because today I'm here to edumacate you about the various vulgarities related to everyone's favorite things: boobs!

Here are some of the very breast Japanese netspeak slang!

ぼいん (boin)

anime big boobs

Those who know a little about the Japanese language have probably noticed Japan's profound love of onomatopoeia. Unsurprisingly, they even have one for large breasts. Even though we all know they don't make sounds in real life, whenever you see an anime girl run, you can't help but hear "boing, boing" in your head! That is, you would if you're mentally 13 like I am. Japanese anime fans apparently are the same, as boin, the Japanese net slang for big boobs, comes from boing!

anime running boobs
Side note: Kimono and yukata do not work that way. They're wrapped too close to the body for any bouncing to happen. Sorry to disappoint.

I don't think you need any more images to illustrate the point-this phrase is largely straightforward.

Other slang for "big boobs":

  • 爆乳 (bakunyuu): One step above kyonyuu, bakunyuu are so big they're explosive! I mean, baku directly translates to "explosion".

  • 超乳 (chounyuu): Super boobs

  • バインバイン (bain bain): Also a sound effect for bouncing boobs

  • 巨乳 (kyonyuu): Giant boobs (the word for giant, incidentally, is the same word in Shingeki no Kyojin (Attack on Titan)

Tsunade big boobs

隠れ巨乳 (kakure kyonyuu)

Charlotte Dunois Infinite Stratos

The full phrase kakure kyonyuu means "hidden big-boobs", which refers to anime characters who have large chests, but don't really draw attention to them. Whether this be a choice made by the animators (where all the characters are modestly dressed), or a character-specific trait (a modestly dressed character in an otherwise fanservice-filled anime), plenty of fans find the modesty of a girl with secret assets charming.

Here's a Japanese list of kakure kyonyuu. Examples include Mio Akiyama, Hanayo Koizumi, and Mayu Matsumoto.

Saori oreimo
Kuroneko glaring at Saori's hidden features.

ロリ巨乳 (loli kyonyuu)

Danmachi Hestia
We know where you're looking, Bell.

You can probably guess where this one is going: young or young-looking girls with large breasts! Specifically, this database of loli kyonyuu anime characters has a few different requirements of what characters qualify as loli kyonyuu.

In order to qualify, a character has to satisfy at least one of these points:

  • The character is young enough to be in school
  • The character has a baby-face
  • Their voice is young-sounding
  • The character is short
  • The anime's art style is child-like

As you can see, it's a fairly loose list of rules, and you don't necessarily have to be underage or jailbait to be loli kyonyuu.

Another popular example of loli kyonyuu might be Poplar Taneshima. Don't be deceived by her cute, tiny appearance; as she says, she's an adult!


パイスラ, or π/ (paisura)

Himouto! Umaru-chan
Himouto! Umaru-chan

When well-endowed girls carry messenger bags or wear seatbelts, the strap sits in between their, erm, plot, really highlighting them. While this happens in real life, it's quite popular in anime, even in fantasy series such as Chaos Dragon. Heck, there's even a subreddit all about the boobstrap. (Goes without saying, but it's NSFW.)

The name paisura literally translates to boob-slash ('pai' is the second half of oppai, Japanese for "boobs", and 'sura' is the abbreviation of surasshu, the Japanese pronunciation of "slash"), which is why you might see paisura written with the Greek letter for pi, and a forward slash.

Koufuku Graffiti
Koufuku Graffiti

Chaos Dragon: Sekiryuu Seneki
Chaos Dragon: Sekiryuu Seneki

つるぺた (tsurupeta)

The opposite of kyonyuu, tsurupeta refers to both flat chests and girls with flat chests. Touhou fans might be familiar with this "flat-chest song":

pettan song

Other slang for flat chests:

  • 無乳 (muchichi or munyuu): no boobs

  • ペチャパイ (pechapai): flat, also a song sung by Brief and Trunks

  • まな板 (manaban): cutting board

  • 盆地胸 (bonchi mune): basin-chest (yeah, I don't understand this one either)

  • 大平原の小さな胸 (taihigen no chiisana mune): the small chest of the great plains (your chest is so flat it looks like the Great Plains)

  • ちっぱい (chippai): a portmanteau of chiisai (small) and oppai (chest)

louise flat chest zero no tsukaima

Fans of the DFC (delicious flat chest) have no need to worry; there is no end of flat-chested characters in anime! Tsundere characters like Louise often possess this trait.

谷間ホール (tanima hole)

Literally translating to "valley hole", this term refers to any inexplicable openings or cuts in a character's clothing that reveals the character's cleavage...valley. This is also known in English as "cleavage window".

Love live boob sweater

The most famous example is not in any specific anime, but these keyhole sweaters that took the internet by storm.

下乳 (shitachichi)

This is another slang that has a direct English equivalent: underboob!

Harribel Bleach underboob
Not only does Harribel display underboob, but she also has a tanima hole under her underboob!

Yoko Littner underboob

Yoko Littner's glorious underboob from various angles, even.

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