Nikaido Aya, a sheltered young lady, is targeted by her father's rival organization. The despicable plan is to train Aya, who is still innocent and doesn't know much about sex, into a lewd sex slave and use her as a hostage in negotiations. She desperately resists, but soon realizes that her anus is incredibly sensitive. She reacts to the overwhelming torture and is remodeled into a masochist. The angelic, innocent and fragile girl is transformed into a succubus.