One day, he overhears his girlfriend Yui complaining to his childhood friend Mio that he is terrible in bed and never makes her feel good. The words echo in his head until he desperately masturbates, wishing he knew how to improve. Mio suddenly walks into his room and offers to teach him how to pleasure a woman. Though bewildered, he accepts, beginning a hands-on sex lesson with his meddlesome childhood friend, who happens to cum remarkably fast herself.