A boy named Tetsu watches lazily as a mysterious white creature appears atop a tall building. He names another one of the creatures "Cenco" and lives his life as a high school student secretly with it, using its ability to change its shape at will to remain hidden. However, one day a girl who goes to his school learns his secret and a mysterious boy named Shuu appears and attacks Cenco, leading to an eruption of unexpected events...

It seems as though the disturbance is over when another girl named Kaname shows up looking for Shuu. Her appearance signals the beginning of a new turn of events for Tetsu, Yuki, and Cenco.

[Source: official website via AniDB]