One day, Amatsuga Hikaru, a junior high school student living in Kitakagami City, meets the mysterious "Ude"-shaped mechanical life form Alma. Alma attempts to bind to Hikaru's body in order to obtain energy from him, but fails. To his surprise, it binds to the hoodie that Hikaru was wearing. Meanwhile, the "Kagami Group," a large corporation that plans to enslave the Mecha-Udes and turn them into weapons, is in pursuit of Alma. ARMS, an organization working to save and free the Mecha-Udes, also searches for Alma. Hikaru, unable to abandon the weakened Alma, puts on the hoodie that Alma has bonded with and gets caught up in the great events unfolding among the Mecha-Ude users......

[Source: official website]