Kimono Wife's Writhing: Soft SM Edition (1999)

Masamitsu Ichimori presides over a haiku doujinshi association, but behind the scenes he is actually running a sex club centered around doujinshi. Masamitsu's wife was trained and shown off to her coterie. The wives of the doujinshi also participated. Masamitsu's younger brother Hiroto, who lives with Masamitsu, is peeking in from the next room with a knife in his hand. He believes that he is possessed by something, and Hiroto sets out to kill them all.