Although very different in tone and content from his award-winning features “Summer Wars” and “Wolf Children,” “The Boy and the Beast” confirms Mamoru Hosoda’s reputation as one of the most interesting writer-directors working in Japanese animation.

After the death of his mother, a sullen boy named Kyuta flees the uptight relatives who assume care of him. As he wanders through Tokyo’s Shibuya shopping district, he stumbles into a series of alleys that lead to the Juntengai, a parallel world inhabited by monsters. In the alternate city, he meets the bearlike Kumatetsu, a powerful creature who is a candidate to succeed the ruler of the realm.

But for all his martial skills, Kumatetsu is crude and rough. Although Kyuta disdains the creature’s sloppiness, he envies Kumatetsu’s strength and asks to be trained. This mismatched pair doesn’t forge a simple “Karate Kid”-style student-teacher bond. As they bicker and learn and grow, Hosoda skillfully juxtaposes broad humor with deeply felt emotions. Kumatetsu and Kyuta must confront linked crises that threaten the future of both worlds. Kyuta battles not only an external foe but the darker side of his nature in a spectacular confrontation that evokes “Moby-Dick” — a dazzling blend of drawn and CG animation.

Hosoda brings emotional depth to what could easily have become a formulaic martial arts saga. Instead, “The Boy and the Beast” is a bracing tale of two flawed individuals who find the love and discipline they need to assume their rightful places in their respective worlds.