Bakemono no Ko

A boy named Ren, struggling with grief, accidentally falls into a hidden world of beasts known as Jutengai. There, he is given the name Kyuta and becomes an apprentice to a bear named Kumatetsu, learning the art of swordsmanship. Kumatetsu faces his own challenges, and the boy and the beast may have much to teach each other. However, Ren's presence in this world puts both Jutengai and his own at risk, requiring more than just lessons in life to overcome the dangers ahead.