Here is the summary of it for those who have not heard of this anime. Like Nabari no Ou, this anime was released in April.

The story revolves around high school student Akira Nikaido, a typical slacker living a normal life. That is, until he meets the mysterious Shirogane, a man who suddenly appears and tells him to meet him at the school that night. Though he is skeptical, he goes anyway, and subsequently gets attacked by a shadow monster. Shirogane convinces him that the balance between the human world and the shadow world has been distorted, and that Akira must become a "shin", which is a creature of the shadow world, in order to help restore the balance.