Hiro Okamura is a young boy who was saved by Superman.
In Japan, inside a bullet train that cannot be stopped, there is a small boy, named Hiro Okamura, who is playing with his robots and toys when suddenly the train runs at full speed to a fatal accident. Fortunately Superman succeeds in saving the train, slowing it down and no one gets hurt, but then nervous people start to question him about his origin and if there are more aliens like him, that they should be afraid of. Hiro seems to run away from the train, as if he is afraid of Superman, who just tries to explain that he needed the world to know that not everything out there is a threat.
In the Comics
Hiro Okamura a.k.a. Toyman is a teenage mechanical genius from Japan, who uses more technologically advanced devices than the traditionally-constructed contrivances the original Toyman, Winslow Schott, uses and his work is largely whimsical in nature. Many of his inventions are inspired by anime and manga, including giant mecha (notably his giant Composite Batman-Superman robot).
Hiro shows up in Metropolis in a giant Super Robot fighting Metallo, claiming the cyborg's equally-giant body was based on material stolen from his grandfather.
He later becomes an ally to Superman and Batman and he aids the two in destroying a kryptonite meteor that threatens the Earth. He strikes a deal with Batman to provide him with various technological implements.
Okamura later fakes his own kidnapping at the hands of Schott, forcing Superboy and Robin to search through his complex to save his life. Realizing his loneliness, Superboy and Robin extend their friendship to the boy. Okamura joins Robin and the other Teen Titans at Titans Tower for Superboy's funeral, clutching a Superboy action figure.
In Superman/Batman #45, he offers to assist the duo in their quest to rid the world of kryptonite, using spider-like nanobots to collect kryptonite molecules in the air. His offer becomes a necessity as Lana Lang, in a last-ditch effort to get rid of Kryptonians and keep LexCorp afloat, turns a set of Kryptonite caches into "dirty bombs", which irradiate the entire planet. Hiro comes to the rescue, settling for a Power Girl-bot to "date". Instead, he gets his dream date, a dinner in Paris with the real Karen, and the status of honorary member of the Justice League.
A future version of Hiro, allied with a power-hungry group of Titans, travels back in time to modern day to cement their power-base in Teen Titans #52.
Hiro appears as one of Winslow Schott's androids in Action Comics #865; given the unreliable nature of Schott's narration, Hiro status as his android creation is suspect.
In the New 52, Hiro, also known as Toymaster, created a beta version of a game that connects the real world with a virtual reality with the only desire for gamers to kill Batman. When he tried to attack Batman they chose Nightwing to be the one to strike but since things got out of control Hiro helped Batman against Dick. They stopped him but later they were attacked by Mongul.
- Showing young Hiro playing with his toys, is a reference to his comic book counterpart where he is known as the third Toyman. He is obsessed with toys but unlike his predecessors he is not a villain but an ally to both Superman and Batman.