My Imouto: Koakuma na A-Cup

Mitsuru Utsumi endures daily verbal abuse from his step-sister Miyu, who acts like an angel in front of their parents but becomes a devil when they are alone. Their strained relationship weighs heavily on him, and he struggles to find a way to improve it.

One day, Mitsuru discovers that Miyu has a complex about her small bust size. When he unwisely mentions it, she explodes in anger. In the ensuing struggle to restrain her, they lose their balance and fall. Staring at her face up close, Mitsuru becomes acutely aware of her cute features, the warmth of her body, and the scent of a young girl—sparking an unexpected shift in their dynamic.