A sadistic older brother with a lolita complex plays pranks on his obedient younger sister, Kyoka, gradually giving her increasingly intense sex education. Kyoka deeply loves her big brother and starts studying sex diligently to meet his expectations. As her erotic side is slowly drawn out, she becomes more and more masochistic. Eventually, she gets excited while being anally penetrated, facing away from her brother, her buttocks slapped as he performs deep throat on her. The transformation from a pure-hearted sister into a deeply submissive girl is erotic and captivating.