At first, Akira Nikaidou considers his life ordinary and lacks motivation in high school. Things change when he meets Shirogane, a mysterious figure who asks to meet him at night on school grounds. Despite his hesitation, Akira agrees, only to be attacked by a shadow monster. Shirogane explains the unbalanced relationship between the human and shadow realms, and convinces Akira to become a "shin," a being from the shadow world, and help to restore equilibrium.