Momonari Junta is an ordinary teenager who has an unusual allergy. You see, Junta has a woman allergy. Yep, you read right. Women. Whenever Junta sees women in any sexual way (a little skin here, a body part there), Junta tends to throw up. However, the only girl he's not allergic to is his childhood friend Ami who he sees more of a friend than as a woman. But, when Karin makes a visit and shoots him with a strange bullet, his world changes. Now, Junta seems to be able to change into a Megaplayboy who has super strength, speed, and fighting skills. He even has the ability to make all the ladies swoon. Thanks to his newfound "gift", both Tomoko and Kotomi fall in love with him, much to Karin's chagrin. Now Karin sets out to stop him from permanently becoming the Megaplayboy. In order to do that, she tries to match him up with Ami, who is unaffected by the Megaplayboy. Should, Junta and Ami get together, Junta would no longer need to change into the Megaplayboy. But Karin didn't take into account, that Junta actually loves her. Even more disturbing for her is that she seems to share that feeling.