My friends know about it, not my family though. I wish I could talk to my friends about Hentai, some of them watch anime but the well-known mainstream ones such as One Piece or Naruto. Even though they like those anime-tachi they're not into hentai.
No-one knows about it from what I know, still my parents allow me to have privacy and don't really seem to care what kind of hobbies I have as long as they aren't illegal illegal or sick
And being an anime fan, it's the norm for me to be teased about the whole hentai subject when friends are around ^^
Only my best friend knows, known him for 10 years so he knows about everything.
Lolicons and hentai. He thinks it's sick, but has no problem with it when I am not trying to get him into it.