Like most teenagers, Mashiro Ichijo has a secret. But Mashiro's secret is that he's neither fully male nor female! So far, Mashiro's been able to live his life as a boy, but all this changes when he's informed of a new class he must take in order to graduate from his elite prep school. To pass, he must find the "Key"--And the only way to find it is to enter into a nightmare world where his body and soul are put at the mercy of the worst kind of enemies: his classmates!