Akiko (1996)

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.