Treasure Ship: Latitudes of Lust

Original title: 色道四十八手　たからぶね

Newly married Kazuo is troubled by the word "Takaraboin" that his wife Chiharu muttered in her sleep. One day, Kazuo learns from his uncle Kenji that "Takaraboin" is a sexual position. When Kazuo finds out that Chiharu had been dating Kenji before they were married, he decides to take revenge together with Kenji's wife.