Image boards have become a popular web pastime in recent years. If you've been to places like 4chan, 7chan, and the like, you've seen a unique culture that mixes illustrated and photographic art from both Western and Japanese culture. After you browse these places for awhile, it starts to become noticeable that Japanese and English are mixed together so much, you need a foot in each culture to understand what's going on.
So here's a guide to the most common Japanese words you'll find in the world of image boards. Keep in mind that these places are inhabited mostly by anime, manga, and video game fans, so most of the terms have to do with this culture.
anime - Japanese animation. All animated cartoons originating in Japan.
baka - A fool, or art representing foolishness. Disney's character Goofy would have considered baka.
bancho - A delinquent or rebellious boy.
bara - A gay man, or art appealing to or depicting gay men.
bishojo - A beautiful young woman, older than adolescence but younger than university age.
bukkake - A fetish for messy sex, and art depicting this fetish.
burikko - An adult pretending to be a child. Features in art depicting age-play.
-chan - A suffix meaning "relating to;" also a Japanese honorific.
chibi - A short, small person or a very young child. Also a specific anime / manga drawing style, making a character appear dwarfish or distorted. Western cartoon elves might be considered chibi.
cosplay - The activity of dressing up as a favorite character from anime / mange. Frequently done at comic book conventions and other fan events.
desu - A short Japanese word that links a noun and verb, literally translated as "it is." Image boards have taken this as a meme, often reiterating "desu desu desu," for various reasons, including to tease the newbies or stubbornly persist in an argument.
doujinshi - Self-published work. The equivalent of desktop self-publishing for manga.
ecchi - The generic term for sexual material.
futanari - Hermaphrodites, or art depicting hermaphrodites. Half-male-half-female.
gaiden - Side or supplementary material. In image boards, gaiden would be some four-panel cartoons of manga characters, depicting events that do not count in the manga itself. A side-story or spin-off.
guro - Very gross pornography depicting extreme injuries, mutilation, or death. The manga equivalent of "snuff porn."
hentai - Erotic bondage manga. Most erotic Japanese illustrative material falls into this category.
hikikomori - An otaku taken to the next level: a loner and outsider whose only interest is anime / manga fandom. The equivalent of a Western "basement geek," only suggesting a neurotic, unhealthy degree of both obsession and isolation.
itasha - The subculture of decorating a vehicle with decals of manga / anime characters.
josei - A manga genre appealing to adult women. The equivalent of Western soap-operas.
kaitou - A mysterious. elusive thief. Also someone with phantom-like aspects. A stealthy person who lives in the shadows. The equivalent of Western rogue or hobbit.
katana - A Japanese sword. About 99% of the time when you see ninjas and samurai with swords, they're shown wielding katanas.
kawaii - Meeting the Japanese standard for "cute."
kawaiiko - A cute child.
kei - Originally a sculpture style used to depict Buddha. As opposed to the more familiar (to the West) vision of Buddha as a jolly, laughing fellow, Japanese Buddhas are slim and serious.
lolicon - A slang term shared between Japanese and Western culture, for the preference for child-like depictions of women.
manga - Japanese comic books. All graphic, printed media of a cartoon nature originating in Japan.
mangaka - A manga creator. Japanese for "cartoonist."
manzai - A style of humor involving a comedic duo of one "straight man" and one "funny man." In Western culture, Abbot and Costello would have considered manzai.
mecha - Anime or manga involving large, armored, warrior robots, usually piloted by a human inside.
meganekko - The attraction to girls who wear glasses. Anime or manga depicting "geeky" girls.
miko - A female temple attendant. The equivalent to a Western nun.
moe - A slang term for a fan of anime or manga, or the attraction to anime and manga characters.
neko - A kitten or a cat, especially when shown as being cute. Also applies to describe a woman in a cat costume, or half-human-half-cats.
oekaki - Scribbling and doodling. Amateur art by fans.
ojou - A high-class or wealthy woman.
omorashi - A fetish for urination. The equivalent of Western "water sports."
oni - A demon or evil spirit.
oranyan - A male who is by turns aggressive and aloof, and sweet and charming.
otaku - A very strong fan of manga, anime, or video games. More serious than moe, not as serious as hikikomori.
pokemon - The most famous anime / manga / video game franchise in Japan.
sakura - A cherry blossom. A very common artistic theme in Japan.
seinen - A manga genre appealing to adult men. The male equivalent of josei.
sensei - A teacher or master.
sentai - Japanese superheros. Also reiter to military heros; in the West, Hercules and GI Joe would both fall under the category of sentai.
shibari - Japanese bondage, incorporating rope bondage raised to an intricate and specialized art form.
shinigami - A Japanese angel of death, in mythology. The equivalent of the Western "grim reaper," although shinigami are a whole class of entities and not just one.
shojo - A manga genre appealing to young women and girls. The younger equivalent of josei.
shonen - A manga genre appealing to young men and boys. Usually action and adventure stories.
shotacon - The Japanese version of "boy's love," the depiction of young boys in an erotic context. The male version of lolicon.
sukeban - A delinquent or rebellious girl.
tan - A suffix meaning a character used as a mascot for a product. For instance, characters used to represent different computer operating systems are "OS-tans."
tsundere - A female who is by turns aggressive and aloof, and sweet and charming.
yakuza - Japanese gangs and gangsters. Organized crime. The equivalent of Western Mafia.
yandere - A psychotic stalker. A genre of Japanese manga / anime depicting shy, quiet people who become smitten to the point of obsession with someone, ever turning violent and abusive, maybe even murderous.
yaoi - Japanese manga / anime depicting male homosexuals but intended for females. In the West, if you made fiction especially for "fag hags," it would be called yaoi.
yuri - A lesbian, or art appealing to or depicting gay women.