Keisuke is a timid and nerdy high-school teacher by day, and a leather clad rapist "superhero" by night. One day, one of Keisuke's students is found dead, and her death is ruled an accident. Keisuke and the girl's mother don't believe her death to be accidental – and upon investigation, Keisuke and Uncle Shotoku unknowingly delve into an underground world of shady cops, scummy drug dealers, corrupt teachers, and a rape-porn ring. Of course, with Rapeman's upstanding moral values, he must do something to avenge the young student's death, bring down the criminals and right wrongs through penetration!

Naoto Kiba takes on the task of protecting thug Junpei who embezzled 500 million yen from Okinawa's largest gangster gangs, Soryu-kai.