My Brother's Wife (2004)

All his life, Takashi has been compared to his older brother, Satoshi. Satoshi is smarter. More athletic. More handsome. More successful. But despite the constant reminders that he's "not as good as his brother", Takashi was never jealous because Satoshi took him in after their parents died. But that was before Satoshi stole Miwa, the love of Takashi’s life, and married her. Miwa, both incredibly beautiful and kind, she captured Takashi's heart long before she ever agreed to marry his brother. And now that she’s Satoshi's wife, Takashi sees her every day. Sees her with him. Hears her having sex with him through the bedroom wall. And each day Takashi's jealousy towards his brother grows a little more.