Promiscuous Wife in Heat (1991)

After his wife and child committed suicide, Sasaki was so shocked that he quit his job and has been living a modest life painting. Then, by chance, he meets up with an old colleague and heads to the home of his colleague's wife, Sachiko, who is waiting for him. In fact, Sachiko and Sasaki have been having an affair for a long time, and that day they have sex next to their colleague as he sleeps. Sasaki also begins to have a physical relationship with Sachiko's younger sister.