In Bakemono no Ko, nine-year-old Ren is abandoned by the last person who had ever shown him kindness and pushed to the edge of a family that no longer knows what to do with him. With nowhere left to turn, he escapes into the streets and alleyways of Shibuya, where he runs into Kumatetsu, a fearsome beast who drags him into the beast realm of Shibuten.
For Kumatetsu, Ren seems like an unexpected opportunity: the boy could become a disciple and help him prove he deserves to replace the lord of the realm once he retires. Yet strength alone has not won Kumatetsu any followers, and his cold, combative personality has left him isolated despite his skill. Ren, meanwhile, is simply looking for somewhere to belong, and the two agree to help each other pursue what they lack most.
As Kumatetsu trains the boy, who comes to be known as Kyuuta, their arrangement grows into something deeper than either expected. Over the years, the bond between boy and beast becomes a source of challenge, guidance, and understanding, revealing that the distance between their worlds is smaller than it first seemed.