Hajime visits his girlfriend’s home hoping for sex, but she is still too serious and reserved to sleep with him. Her adult sister Mao is the complete opposite: bold, sexually open, and blessed with pale skin and huge breasts. Mao seduces him with whispered dirty talk and skilled breast rubbing, and he quickly gives in to cheating sex. He abandons his restraint and shoots ten loads during her titjobs, becoming completely addicted to her shameless temptation.