At the Ministry of Science, the zealous Professor Ochanomizu and his colleagues work to reactivate Atom, the first robot possessing a human heart. Atom is the magnum opus of the mysterious Professor Umatarou Tenma, who constructed the android to take the place of his late son, Tobio. Yet, after Tenma inexplicably deactivated his creation and vanished, Ochanomizu is determined not to let such a significant scientific advancement be wasted. Although Atom looks like a nine-year-old child, he boasts extraordinary strength and intellect, along with a notable conscience and compassion that match those of humans. Unfortunately, the mechanical boy soon encounters rejection and discovers that not everyone is as accepting as Ochanomizu. While automatons have become part of society, they are regarded merely as tools and even viewed as a looming threat to human supremacy. Hoping for a world where humans and robots can thrive together, Atom devotes his life to safeguarding both and encouraging them to build authentic connections.