If memory serves me right. It is illegal to show what is between a woman's legs in Japan. Except for manga/animé or anything depicting being attacked by demons/monsters.
Article 175 of the Japanese Criminal Code is the culprit. It basically says "No obscenity". There's been several interpretations of the statute but mostly it came down to that old bugaboo, defining obscenity. Culturally/historically pubic hair was considered obscene in Japan so that area was covered then obscenity seemed to be dodged. Although over the last few years that's changed somewhat and one sees pubic hair in non-action scenarios, i.e. nude poses, etc. Whenever there's action, like hanging some woman by her breasts they cover the pubic area.
Tentacle porn..that I don't understand at all.
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