Is Toumei Ningen (OVA) hentai?
English title: The Invisible Stud
Yes
Rated Rx (Hentai) on MyAnimeList.

OVA · 2006 · 2 episodes · Rx - Hentai
Hentai
Mie happened to pick up medicine that an old man dropped. When he took the medicine, his figure disappeared. Soon he went to a public bath to peep, and began to molest. Then, he went to an all-girls school. (Source: AnimeNfo)
View on MyAnimeListShare
Check another title