Sexual Confessions at Twenty: Leaning Back (1978)

The beastly desires lurking in a 50-yen stamp assault soft skin once again today. Based on a true story of a man who used the pen pal section of a magazine to rape women, eventually leading to murder, Eiji (Asami), a mechanic at a car factory, is being taken advantage of by his senior colleague, Tashiro (Kato Hisashi). Eiji Eiji develops a crush on Reiko (Miyai), Tashiro's girlfriend, who teases and provokes him, and unknowingly steals her underwear. As a result, Eiji is forced to condone Tashiro's illegal resale of car parts. One day, Eiji's eyes fall on the pen pal section of a magazine, and he reads an ad seeking a boyfriend, and excitedly begins writing replies one after another. As Eiji goes on dates with the women who have written to him, his desires grow stronger. And so, Eiji begins having relationships with the women he's been writing to as pen pals.