Modern Japan. Momonari Junta is an unusual guy. He has an allergy to women—at the slightest hint of an erotic scene, he starts turning inside out. However, after a randomly administered DNA modifier injection, he temporarily turns into Mega-Playboy—the absolute opposite of himself, the "ideal man" and idol of all girls in the world. Only two girls are interested in Junta as he is. One of them is Aoi Karin, a patrol officer from the future who gave Junta an incorrect injection; the other is Kurimoto Ami, whose marriage was arranged by Junta"s parents even before his birth.