From Go! Comi:

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!

A European mystery romance, "Glass Shoes" - the long-awaited conclusion!! The clever Bild, who has figured out that it's Al's spirit currently inside Saylie's body, begins a plot to get rid of Saylie, who will become an obvious obstacle in the future... Meanwhile, Debroyl asks for Saylie's hand in marriage, claiming that he loves her just the way she is, however...?!

Three boys in junior-high who cross-dress because of differing reasons meet each other through a cross-dressing community website, and decide to meet up in real life. "Parou" started cross-dressing because he wanted to attract a heterosexual boy he liked. "Marika" is transgender and identifies as female. Lastly, "Yui" is an antagonistic boy who adopted the persona of his older sister after her death. In contrast to Parou and Marika, Yui is sorely disappointed at the meeting.