In a not-so-distant future, a brilliant and melancholic scientist named Tenma loses his son, Toby, in a tragic accident. Worn down by grief, he decides to create a robot that can replace the boy: a small android resembling Toby, equipped with incredible skills and powers, making it an unprecedented innovation. However, despite its appearance and superhuman abilities, the young robot faces rejection from those around it and an internal struggle to accept its new identity.
As the human world and robots coexist with underlying tensions, the protagonist becomes a fugitive, an outsider seeking to prove his worth. With the help of new friends, including a curious girl who helps him understand what it means to be human, he embarks on an adventure through the futuristic city of Metro City. Along the way, he encounters formidable adversaries, including other robots created for dark purposes, and discovers both love and friendship, transforming his view of the world and himself.
The journey of this robotic hero will lead him to confront not only his own existence but also the ethical dilemma surrounding creation and sacrifice. On his fearless quest to be recognized as the true hero within, he becomes a symbol of hope for all, demonstrating that being "human" goes beyond flesh and metal.