Season 1

Hiro was an office worker at his father's company, Yamagato Industries, in Japan, until one day he accidentally teleported to the future. Here he saw that on November fifth, a bomb would blow up New York. He then returned back to October second. He with his friend Ando traveled to the United States.

There they went to Las Vegas following Hiro's comic from the future created by the precognitive Issac Mendez. After being beat up for cheating and dumped near a desert diner in the outskirts of Las Vegas, a fight ensues, and Ando and Hiro split ways. Hiro meets "flying man" Nathan Petrelli at the diner. Nathan gives him a ride back to Las Vegas, in a car. This entire time Hiro tries to warn "Mr. Issac" that in five weeks he will be dead, as seen when he went to the future. One call, Peter Petrelli picks up and tells Hiro the message, "Save the Cheerleader, Save the World."

Reunited, Ando and Hiro go to the Burnt Toast Diner to wait for further instructions from Peter. Here Hiro meets Charlie who is killed by Sylar. To save her, Hiro goes back in time, but all for naught. Returning to the present, Hiro thinking his quest to save the cheerleader has failed meets Issac. Issac paints Hiro battling a dinosaur, so Hiro vows to get the sword. Taking the painting as collateral, Hiro travels to trade the Linderman group, an avid collector of Issac's paintings for the sword. Hiro's father attempts to stop Hiro, ripping the painting, but is soon persuaded to let Hiro go about his quest. Hiro reaches the sword and trying to escape teleports to the future, where he is captured by Future Matt Parkman.

Future Hiro, Ando, and Future Peter save Hiro at the cost of Future Hiro's life. Hiro and Ando return to the Present and confront Sylar. Sylar breaks the sword and Hiro and Ando get it repaired. While Hiro trained with his Dad, Ando assuming Hiro would give up his quest, tries to confront Sylar again. Hiro saves Ando and returns him to Yamagato industries. Hiro then proceeds to confront Sylar at Kirby plaza stabing Sylar in the chest. Sylar flings Hiro at a building as a last effort and Hiro teleports finding himself in Kyoto, Japan in the year 1671.

Season 2

Hiro is in Kyoto, Japan in the year 1671. He sees the occurance of an eclipse and then is faced by arrows raining down upon him and another man under a symbol on a flag that matches Takezo Kensai's sword. Hiro freezes time to save his hero from an untimely fate only to discover that it was a replacement sent there by the real Takezo Kensai, an englishman dressed as a samurai who had planned on using the decoy as a distraction to snipe his enemies from a tree with a crossbow. Yaeko, the one foretold to be Kensai's princess, is a swordsmith's daughter that repeals her father's payment of his sword. She then goes off to face the bandits herself. Wanting to fix the mistake of altering the past, Hiro donnes his heroe's armor and confronts the bandits in an effort to save Yaeko. Hiro then chases off the bandits by using his powers to collect all their weapons in the blink of an eye. Hiro had saved Yaeko and Kensai's reputation, and had sparked Yaeko's love for Kensei.

Hiro then returns to Kensei and sways him to be the Hero the ledgends had been written about. However, as the two leave Kensei is shot with arrows and killed. When Hiro removes the arromws Kensei shows his unknown ability to heal and regenerates to life. Hiro decided to test Kensei to see if he had truely become the hero of ledgend and forces him to fight 90 ronin to retrieve the "fire scroll". Succeeding, Kensei decides to become the hero that Hiro sees him to be. To this, Hiro decides to leave but falling in love with Yaeko himself and the desire to make sure the timeline is secured, makes Hiro stay.

The Trio of Kensei, Hiro, and Yaeko travel to the dreaded White Beard's camp to save Yaeko's father. However, once Yaeko is save Hiro, weakened by his love, Admits to loving Yaeko and the two kiss much to the pain of the secretly onlooking Kensei. Kensei grows angry and joins White Beard and captures Hiro, Yaeko, and her father.

Hiro, captured in White Beard's camp and drugged on opium to prevent him from using his powers, is freed by Yaeko who had freed herself from her own bindings. Hiro is able to focus long enough to free Yaeko and her father. That night Hiro goes preform the next to last trial of Kensei, to save all of Japan, destroying White Beard's guns. Hiro goes to light the gunpowder cache, but is stopped by Kensei. During the battle Hiro tries to persuade Kensei to change ways and be the hero he was supposed to be. However, Kensei vows that as long as he lives he will destroy everything he holds dear. During the battle, a lamp is knocked over and before it explodes Hiro teleports away.

Hiro returns to Yaeko. Hiro is upset and tells the end of Kensei's story to her. She then tells Hiro that as long as she lives she'll tell the story of the real Takezo Kensei, Hiro. So,, like Kensei, Hiro "cuts out his heart", and returns to his time.

Back in his own time, Hiro discovers his father has been killed. Hiro attempts to save his father but is persuaded that he cannot play god with his powers and must let his father die. Hiro, however, uses his ability to discover his father's murderer, only to discover that it was Kensei.

Hiro begins his quest to stop Kensei. Discovering Kensei's real name, Adam Monroe, Hiro travels back to 1977, where he sees his father imprison Adam for almost releasing a deadly virus. Hiro learns that this virus will be contained in the Primatech facility in Odessa, Texas. Hiro goes to the facility via teleportation and stops time. He searches for Adam only to find Peter Petrelli. Hiro explains to Peter why he is here and what Adam plans to do, but Peter is blinded by the fact that Adam healed his brother after Peter exploded. The two battle but Hiro is knocked out.

Hiro is awoken and joined by Nathan Petrelli and Matt Parkman who are also trying to stop the releasment of the virus. Hiro teleports to Adam and Hiro tells him that he should not of let him live long ago. Grabbing Adam's arm the two disappear. Hiro puts his once hero, Adam Monroe in a casket and buries it in a Japanese graveyard.Hiro later tells Ando that Adam will not hurt anyone ever again.