Theo and the Metamorphosis is an adaptation of the eponymous novel by Natsuki Ikezawa. The story revolves around a 27-year-old man with Down syndrome called Théo who lives with his father in a house hidden away in the thick of a forest. They live together in harmony with the surrounding flora and fauna but, one day, his father goes away, leaving Théo alone with his inner world. He embarks upon an odyssey which sees him reinvent himself, open himself up to the world, and experiment with freedom, attempting to discover the nature of things, but also the nature of beings.