The protagonist is troubled by his beautiful classmates who have taken over his home where he lives alone.

One day, while being used as an errand boy by Luna, a gyaru who was relaxing as if she owned the place, he got aroused by her erotic body and had an erection.

Luna, surprised and intrigued by the protagonist's huge penis, tries to seduce him, planning to use him as a convenient human vibrator. However, she is overwhelmed and defeated by his extraordinary virility! She completely falls, becoming his personal impregnable masturbation toy.

Gaining confidence in his huge penis, the protagonist goes on to conquer and impregnate the top-caste, exquisite gyarus who reside in his house—the ojou-sama gyaru Shiori and the elite athlete Mio—thus completing his harem life of impregnable masturbation toys!