Bizarre bondage lady (1981)

A younger brother picks up a woman on the street and takes her home, and his older sister ties her up with rope, shaves her pubic hair, trains her in a perverted way, turns her into a fine perverted masochist, and then sells her off to a man who is an enthusiast in that field. In the heat of excitement, the master and disciple indulge in incest. One day, the younger brother, who was living this lifestyle, sees a girl on the street. The girl sells a match to a drunkard for 500 yen and shows her private parts by the light of the match. When the younger brother asks her why she does this, she answers that her mother did the same thing. She says that since her mother died, she is doing the same thing to survive. When the younger brother takes the girl home, the fate of the master and disciple begins to change...