After a tragic accident, Keisuke, mild-mannered teacher by day and rapist vigilante by night, and his Uncle Shotoku discover a conspiracy within a Tokyo hospital to sell children's organs to the Hong Kong mafia. Keisuke must use his expertise to unravel the corruption and right wrongs through penetration!

In this first installment of the series - we are introduced to Keisuke: mild mannered school-teacher by day - avenging angel of rape by night - and his goofy Uncle, who together run Rapeman Services. Their "services" are called-upon by a nightclub owner who tells a sob story about having her boyfriend, a current political candidate, stolen by his secretary, and asks Rapeman to "take care of her" as an act of revenge. This is done per the nightclub owner's request - but we soon find that the story was just a cover to cause a bigger scandal that involves rival a seedy rival politician and the Yakuza...

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!

A senator's secretary seeks out Rapeman's services to rape his fiancé who has been brainwashed by a local cult. According to the by-laws of the cult - if the woman has sex with a non-member, then she will be disassociated from the cult, thus bringing the wife back to her husband. This back-fires when the cult does not ex-communicate her - so Keisuke and Uncle infiltrate the cult to get to the bottom of their shady dealings. The resulting investigation embroils the duo in a conspiracy between the cult and a sleazy politician that can only be "righted through penetration"...

Two mysterious tough guys infuriate a local gang after helping an elderly grocery store owner with his debts by robbing a yakuza organised gambling den.