Angel of Darkness (1995)

Angel of Darkness 1995 / 淫獣教師 1995 / 淫獣教師　実写版 , Angel of Darkness Vol 1 , Injû kyôshi - jissha-ban , Inju kyoshi - jissha-ban

At a high school in Tokyo, several of the female students have been moon-lighting as prostitutes. A teacher catches onto this fact and goes about putting an end to it. Things go awry when he discovers he turns into a sex demon with tentacles whenever he gets aroused (huh?). He turns from savior to vilifier, poor prostitute school girls. (Source: TMDb)