The documentary is about making Hayao Miyazaki's final film, The Boy and the Heron. The documentary primarily focuses on Miyazaki's creative process, his relationship with fellow filmmaker Isao Takahata, and his struggles with the film's production. We see Miyazaki grapple with his mortality, his dedication to his craft, and his anxieties about the film's reception. The documentary vividly depicts a legendary filmmaker at the end of his career, wrestling with his demons and trying to leave a lasting legacy.