Tobio Tenma is a gifted 13-year-old boy who lives in Metro City, a futuristic city-state that floats above the polluted surface of earth. Tobi's father, Dr. Tenma, is a famous roboticist and head of the Ministry of Science, but has a distant relationship with Tobi. Dr. Tenma meets the city's obstructive leader President Stone to demonstrate a new defensive robot called the Peacekeeper. To power it, Tenma's friend Dr. Elefun unveils the Blue and Red Cores, two energy spheres which emit opposing positive and negative energy. Against the scientists' warnings, Stone, desperate to win a re-election, loads the Red Core into the Peacekeeper, causing it to go berserk and Tobi, who snuck into the room, is accidentally disintegrated by the Peacekeeper before it can be shut down.