Marina and Airi's mother has left her husband, only to marry a younger man, Kouzou Akizuki. While Marina has accepted their new stepfather, Airi hates him for breaking their family. Furthermore, she soon finds out he is a sexual deviant, sniffing his underaged stepdaughters' underwear and secretly desiring to take their virginity. Their mother is often absent from home, allowing Kouzou to pursue his carnal pleasures to his heart's content. Unable to resist the beauty of adolescent girls' bodies, Akizuki prepares a powerful aphrodisiac and uses it on Airi. Intoxicated with the drug, she can no longer control herself and gives in to her stepfather's perverted demands. She soon discovers the merits of this new relationship and plunges headlong into a whirlpool of sexual degeneracy. Satisfied with the drug's irresistible effect, Kouzou proceeds to utilize it further, coercing various girls to quench his thirst in the most embarrassing ways.

Young men and women are supposed to be interested in the opposite sex. They're supposed to be interested in sex, period. But the students at the prestigious Nobel Academy have been exhibiting unusually strong urges lately. When one of the female scholars spends her entire summer vacation masturbating in her room, her father calls on the Central Genetic Research Institute for help. Special Agent Akiko is assigned to investigate forthwith, and goes "undercover" to discover exactly what possesses the student body.