"The state of mind that can be reached through abstinence is limited." Nagao Seiji, known as the walking sex organ. Even after his wife ran away, his womanizing wickedness doesn't change. Seiji's son Tamotsu is dating Mahiro-chan, who has a cute face and soft breasts, but to avoid being sexually objectified by his father, he makes her dress up as a man when they do naughty things at home and introduces her to his father as "Mahiru-kun," a new transfer student. One day, Seiji comes across Mahiru-kun waiting for Tamotsu on the street, and in his kindness, he calls out to him to wait at his house...