The story revolves around high school student Akira Uehara, sensitive and demure by nature. Despite that he has a large crush on the most feared and violent girl in school--Nanako Momoi, who seems fragile and cute, until she opens her mouth.

One day Momoi is absent from school for unknown reason and someone is needed to bring her homework to her. Though most students push it off to each other, Uehara willingly volunteers to bring Momoi her homework. He arrives at her house to find it unlocked and seemingly empty. He enters and stumbles on a secret passage, which leads to the laboratory of Momoi's mad scientist grandfather, who is using his own granddaughter as a test subject of his new invention.

He is about to save her, but the situation turns on him for the worse when Momoi successfully persuades her grandfather to use Uehara. In attempt to get Uehara, Momoi's grandfather accidentily presses the lever that activates the machine and the end result is that Momoi and Uehara have switched bodies.