Sokubaku Jouzu na Koakuma Musume | 射精管理上手な小悪魔娘♪

This is the story of a brother who is a temporary teacher at a school, and his sister who is a student at that school. His impudent sister, Jurina, who never listens to him, is always a headache.

One day, she hears a rumor that the protagonist is on good terms with a female teacher colleague. She confronts the protagonist, ignores his will, and forcibly makes him ejaculate. After photographing his embarrassing state, the words she utters are...

"From now on, I'll be in charge of your ejaculation control forever."