Furin Tsumatachi no Shûmatsu (2002)

Muneo always goes fishing on weekends. His wife, Ritsuko, suspected him of having an affair and hired a private investigator to look into it. One day off, a detective's assistant tailed Muneo as he headed out as usual. Sure enough, Muneo had rented an apartment where he was carrying on an affair. Upon receiving the report, Ritsuko commissioned an investigation into the other woman as well—only to uncover an unexpected truth.