Hiroto is a student who lives by himself. One day, he injured his right hand while protecting his younger sisters. Luckily it was not serious, but they mistakenly thought it was the opposite?! He was excused from school until it healed, and his imoutos forbade him from using it. Of course, it would be quite inconvenient, so they suggested that they will always be by his side, as his ‘right hand’. From that day on, everything that he did with his right hand was left to his younger sisters: eating, taking a bath, doing groceries, going to the washroom, masturbating… “Leave everything to us, onii-chan!”