Set in an alternate version of the Meiji Era, a boy named Sakamoto Ryunosuke returns to Kyoto from Shanghai with his monster (youkai) Nekomaru. The law states that in order to live freely with humans, a youkai must be liscensed. The Kidou Shinsengumi Co. Ltd. is responsible for the capture of unliscensed youkais but must fight with the Tsubamegumi,...