Ichijo Mashiro is your average high school boy. The girls think he's dreamy, he does kendo... and he gets cramps when he's on his period. Perhaps Ichijo isn't as average as he wants everyone to think. In order to graduate he is told that he has to enter a world where he gets to see his classmates in ways he never could've imagined. Once he wakes up from the nightmare the basement room is gone, leaving no trace of the horrifying experience until the following week where he must keep trying until he finds the key to “graduation.” On top of that, when he wakes up he has to deal with classmates who have stabbed him, scared him, and who have learned his secret: he is not really a boy or a girl.