At Rubrum's Akademeia, cadets are divided into twelve classes based on their magical expertise. Kurasame Susaya feels that he is wasting his time with the immature cadets in Class Third, so he strives to be a part of real missions with the elite Class First where cadets take their roles more seriously. With the proposal of a test of courage, however, Kurasame begins to see his class as more than just lazy idiots, but his chances of being a part of the class are taken away after tragedy strikes.

As a result of the disaster, Kurasame and three of his fellow classmates Miwa, Guren, and Kotetsu unite to help support each other, and to defend Rubrum from the outside forces that will do anything to see it fall.