After the sudden loss of his mother due to an accident, Ren wants to be with his father. But because of the court orders, he can’t be with his father as a condition of his parents’ divorce prior to the movie. He refuses to be adopted and chooses to live homeless on the streets of the trendy Shibuya district in Tokyo. One day, he encounters two mysterious cloaked beasts and decides to follow them to an alternate dimension known as Shibutengai, in which its architecture takes influence from feudal Japan. As opposed to humans, beasts highly trained in the martial arts reside there. Ren then becomes a disciple of Kumatetsu, the beast who led him into Shibutengai, and lives the rest of his childhood there.