Astro Boy finds a decommissioned soldier robot on a graveyard planet and brings him home. What follows is a quiet story about two machines learning that friendship matters more than the wars they were built to fight. The film takes the strongest part of the Atom mythos, that a robot can choose kindness over programming, and makes it unbearably human by pairing it with someone just as broken and tired.

Astro Boy is assisting Professor Ochinomizu with planetary exploration when he finds a trash star drifting through space, piled high with robots that can no longer move. On that mountain of scrap he saves Bemu, a soldier robot who narrowly escaped death, and brings him back to Earth. Both are weary of fighting, and a warm friendship grows between them. Then the trash star closes in on Earth, where a collision would set off a massive explosion. As the planet falls into chaos, only one way remains to prevent the crash, and Astro must decide whether he can save both Earth and his friendship with Bemu. This science fiction mecha film is set in the Tetsuwan Atom world.