On Walpurgis Night, in the school basement where eerie incantations echoed, a ritual was being carried out on a beautiful sacrificial woman stripped naked. Twelve years later, Minase Taki stumbles upon a “grimoire” in that basement. Using its secret spells, he succeeds in enslaving the student council president he admires, Shiraki Seina, as his sexual captive. Then, one lewd incident after another begins to occur at the school. What is the Walpurgis Night that closes in on the school’s beauties…?!