My Imouto: Koakuma na A-Cup  

My Sister: Little-Devil with an A-Cup, My妹～小悪魔なAカップ～

The morning at Utsumi household is often disrupted by heated arguments between Mitsuru's sister and brother. This happens frequently, causing anguish for Mitsuru as their relationship with their step-sister, Miyu, remains unimproved. Despite appearing sweet in front of their parents, Miyu can be quite cruel when they are alone. One day, while talking to Mitsuru, Miyu reveals her insecurity about her bust size. Unaware of the sensitivity of this topic, Mitsuru brings it up and Miyu becomes enraged. In an attempt to calm her down, the two lose their balance and fall. As they stare into each other's faces, Mitsuru is drawn to Miyu's cute features, warm body, and unique scent of a young girl.