[5] The film stars the voices of Kōji Yakusho, Aoi Miyazaki, Shōta Sometani, Suzu Hirose, Kazuhiro Yamaji, Mamoru Miyano, Kappei Yamaguchi, Keishi Nagatsuka, Kumiko Asō, Haru Kuroki, Sumire Morohoshi, Momoka Ōno, Masahiko Tsugawa, Lily Franky and Yo Oizumi.

In the Beast Kingdom, the grandmaster has decided he will retire in order to reincarnate as a deity and names two potential successors: the popular Iōzen, who is also the father of two children, Ichirōhiko and Jirōmaru, and the powerful Kumatetsu, who is solitary and lazy.

When he rejects both his father and Kumatetsu, he discovers a powerful void within himself that nearly overwhelms him, until Kaede gets him to calm down and gives him a bracelet that has helped her when she becomes anxious.

When Kumatetsu is declared the winner and the new lord, Ichirōhiko is revealed to be a human who had been found on the streets of Tokyo as an infant and adopted by Iōzen.

Having developed a vacuum in his heart like Kyūta, unwilling to believe that he is a human and not a beast, Ichirōhiko manifests telekinetic powers and seriously injures Kumatetsu with Iōzen's sword.

However, Kumatetsu uses his privilege as the new grandmaster and reincarnates as a deity, taking the form of a sword "to be handled with the heart" in reference to their first training session together.

[19] The film was #1 at the Japanese box office during its opening weekend, replacing Avengers: Age of Ultron, and earning approximately US$5.4 million on 492,000 admissions from 457 screens.

The website's critical consensus reads, "The Boy and the Beast combines familiar parts to create a gripping, beautifully animated adventure with inventive storytelling to match its visual appeal.

[23] Mark Schilling of The Japan Times said that the film "has more in common with the "Harry Potter" series than the usual female-centered Miyazaki fantasy" and would later say that the storyline "stays centered on Kyūta's long, vexed struggle to become not only strong, but also whole.

"[25] Charles Solomon of the Los Angeles Times said the film "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.

"[26] Peter Debruge of Variety called it "an action-packed buddy movie that strategically combines several of Japanese fans' favorite ingredients: conflicted teens, supernatural creatures and epic battles.

"[28] Pat Padua of The Washington Post wrote, "But it is the world of man, not beast, that makes this coming-of-age movie most touching.

"[32] Jacob Chapman of Anime News Network had a mixed response to the film and said "The Boy and The Beast is the kind of movie you put on to please a kid with its loudness and color, but promptly leave the room to do something else.