Saddle up, Fap-chan.
Hentai (変態 / へんたい) is a lot more than animated porn, and there’s a whole world beyond the tentacle sex and school girls in uniforms. Mistranslated by almost all outside of Japan, it translates to “abnormal” or “perverted” – not tentacle porn.
And perverts are served.

You can fulfill all of your fantasies and more, and find more than a handful of things that disturb you on the way. Being animated, possibilities are unfathomable. Nothing is limited to the imagination. Rule 34, people.
But that’s the point: with hentai, you are guaranteed to find something that’s abnormally titillating enough to turn you on, even though it’s a score of paces outside of your comfort zone. If you’re going to be an abnormal pervert, then you need the right tools in your toolbox.
An Abbreviated Guide to Hentai Sub-Genres:
anaru (アナル) – “anal” If it’s going in the butt, it’s going in this category.
anaru zeme (アナル攻め) – “anal attack” It doesn’t just go in the butt, anything goes in the butt – and we aren’t being gentle here.
BE (BE) – “breast expansion” This describes the process of enlarging breasts through science, magic, or general hentai fuckery. There are varying degrees from the flat-chested pachapai (ぺちゃぱい / ぺチャパイ), to chonyu (超乳), which are physically impossible “ultra breasts.”
chinran (産卵) – “egg laying” This involves the (generally non-consensual) impregnation and laying of eggs by insects, aliens, or what-the-fuck-ever.
etchi (エッチ) – sexy material that just isn’t perverted enough to be hentai. Ecchi is a common and incorrect spelling.
futanari (二形 / ふたなり) – “double form” Almost always of a feminine aspect, futanari have both sets of genitals and breasts. Futanari usually involves BE and inkeihidai.
haramase (孕ませ) – “to impregnate” For when being filled with eggs just isn’t enough, there’s incubation and birth!
inkeihidai (陰茎肥大) – “penis expansion” Following the same hentai laws of BE, penis expansion goes beyond the pump to bring you an impossibly large organ to fill any hole.
iryō fechi (医療フェチ) – “medical fetish” Because everyone loves getting violated by a team of doctors and nurses and with their array of medical paraphernalia.
kemono (獣) – “beast” Humanoid beasts that like to take advantage of very human girls and boys.
kemono henshin (獣変身) – “animal transformation” Often resulting of a science experiment-gone-wrong, girls change into humanoid beasts (furries – ファリー), accompanied by all the right animalistic instincts.
niana dōji (二穴同時) – “two-hole simultaneous” DP, mothafuckas!
nuri fechi (塗りフェチ) – “painting fetish” Take getting off to girls covered in paint to the next level by getting off to virtual girls covered in paint.
rinkan (輪姦) – “gang bang” Consensual or non-, if there are multiple partners, it’s a rinkan party.
seifuku fechi (制服フェチ) – “uniform fetish” For those who have a ‘type,’ hentai indulges in uniform fetishes of all kinds. Popular uniforms include: bus tour guide (basu gaido – (バスガイド), gothic lolita (gosu rori – ゴスロリ), magical girl (mahō shōjo – 魔法少女), and office lady (ofisu redi – オーエル).
shikan (屍姦 / 死姦) – “necrophilia” Getting it on with the dead can be accompanied by guro (グロ), which involves the violent shedding of blood in various manners.

shokushu (触手) – “tentacles” Tentacles came about as an attempt to get around Japanese censorship laws. Because the non-consensual attack of a creature from the depths was/is absolutely more acceptable than your everyday penetration…
wakamezake (わかめ酒) – “seaweed sake” Pouring sake on a woman’s body and drinking it from her pubic hair, flavoured with her sweet lady-juices, presumably. Japan’s been serving up uncensored “seaweed sake” since the late nineties due to a change in their notoriously tricky censorship laws.
Yaoi (やおい / ヤオイ) – “boy’s love” – An acronym for “Yama nashi, ochi nashi, imi nashi” (山[場]なし、落ちなし、意味なし), meaning “no climax, no punchline, no meaning,” yaoi pokes at traditional plot structure and showcases young gay love for all fans of slash fiction.
Yuri (百合) – “lily” Yuri is basically the female equivalent of yaoi, except the fact that there tend to be more male fans among the lot.