Mashiro Ichijou, an attractive and popular high school student, has always lived his life as a boy. However, nobody notices that deep down, he resents the fact that his body is half female. He has decided to conceal his femininity from those around him, while in reality, he is insecure about who he is supposed to be.

One day, an unfamiliar nurse asks Mashiro to follow her to the school's infirmary in the basement—an office that has never existed until now. Little does he realize that the moment he steps into the mysterious room, he will never be capable of returning to being the person he was before.

As he struggles to find his true identity, Mashiro must face the disquiet in his own heart, all while protecting himself from the prying eyes of his classmates. Slowly but steadily, the unbecoming truth of the world is laid bare: all its lies and deceit engulfed in nightmares that only unfold in broad daylight.