Shûichi Kagaya, a high school student without stories so far, suddenly becomes able to transform himself into a gigantic monster with an out-of-standard ability. He thus saves Claire's life stuck in a burning house. But Claire discovers her secret and also that she has the opportunity to sneak into the mascot embodied by Shuichi through a zipper. And if Shuichi was not the only one in this case!? What awaits these two high school students now bound by destiny!? Their biggest fight is about to begin!! Let's do only one more... to life, to death!