Masahiko's cute little sister Hina gets a hypnotism app on her phone. She uses it to hypnotism him. The app doesn't work but he decides to pretend it does anyway. What harm could it do? His younger sister is innocent and cute.

"Walk me to the park onii-chan" she asks. "Make me omurice with a ketchup heart". Her demands are adorable and sweet. Then she asks for a kiss. Then she asks for more. Slowly her demands become even bolder until finally "Have sex with me onii-chan". His innocent and cute little sister isn't so innocent anymore.