The Boy And The Beast, Vol. 1 (Manga)

A lost boy in Tokyo, Kyuta, slips into an alternate universe, where he is raised by a bear-man, Kumatetsu, who fights for a living.

Fleeing tragedy and mistreatment, a young boy named Ren hides among the crowds in Tokyo's busy Shibuya district. His efforts to run away are more successful than he realizes when he ends up in the world of the beasts! A rough-living bear named Kumatetsu gives Ren a new life and a new name - Kyuta - but is Kumatetsu really up to the job of being a mentor?