Thicker Than Water (2018)

Kazunari is the half-assed younger brother who appears to be thoughtful and diligent, and his older brother Takuji is a violent troublemaker. Takuji finished his prison sentence for robbery and has made himself comfortable at Kazunari's apartment. Meanwhile, Yuria is competent at work but unattractive, whereas her little sister Mako is pretty but dumb. Yuria has fallen in love with Kazunari, a salesman for one of her clients, but one-day Kazunari and Mako start going out.