A 9-year-old boy named Ren lost his parents, ran away from his guardians, and wandered the streets of Tokyo. There, he met the great warrior Medvezhat, a bear-like creature from a parallel world who sought an apprentice. Ren became Medvezhat's disciple. In the world of monsters, Ren was given the name Devyat, and under Medvezhat's guidance, he began training to become a master of martial arts.