He is portrayed by Masi Oka.
Bored with the monotony and conformity of his job as a salaried employee, Hiro Nakamura turns to his love of science fiction and fantasy as an escape. A bit of a dreamer, Hiro loves the idea of possessing powers, but the reality of it all becomes more than what he expected. Initially a happy-go-lucky fellow with an innocent view of adventure, Hiro's experiences force him to become more serious and determined. Hiro possesses a very strong sense of purpose and a solid moral foundation, and the events of the series only strengthen them. Dying from a brain tumour, Hiro has decided to use his restored time travel power to fix past mistakes and make life better for others around him. However, Hiro is not without flaws: he can be quite clumsy and reckless, especially when using his powers, and he can occasionally be selfish. This is particularly shown when he goes back in time to prevent a girl that he loved, Charlie Andrews, from being killed by Sylar, completely disregarding the possible disastrous consequences of changing the past and affecting the future. Furthermore, if he wanted to change the past, he perhaps should have killed Sylar and prevent a lot of his countless victims from ever being killed, as pointed out by Adam Monroe's hallucination to Hiro when he is dreaming.
Hiro discovers he has the ability to actually affect the space-time continuum, slowing time down to such a point it seems as if it is stopped with sheer power of will. The first noted occurrence is when Hiro supposedly made a subway train late using this power. This is especially notable because a Japanese train being late at all is an extremely unlikely event. Later, he theorizes that he may soon be able to teleport by bending the space part of the continuum. Although this isn't seen, he does seem to teleport from the seating area of a Karaoke bar to a ladies' bathroom on a dare (said in jest) by Ando. While he is on a train he stares at a poster of New York, accidentally teleporting himself to Times Square. However, at the same time he unintentionally moves five weeks into the future. Later, when an explosion threatens his life, he is able to teleport back to Japan, landing at the exact time and place of his original departure.
Although being able to teleport and time travel great lengths at once, Hiro apparently had little control over how much time elapses when he teleports. This shows that, without further honing of his powers, he may not be able to teleport great distances without also travelling in time. He has also frozen time relative to himself. He was able to keep time frozen long enough to fold one thousand paper cranes.
Hiro's rules of time travel haven't yet been explicitly defined. Whether he changes time just by travelling, or whether it's more of a ripple effect is not known.
It should be noted that it appears Hiro's time-traveling powers may not supersede the principles of the self-consistency theory. This essentially states that a time traveler cannot alter history in such a way that he would cause a paradox to occur; rather, the events would self-correct. However, it seems Hiro's powers are controlled by "fate", as not only were his powers disabled at one point, but he traveled in both time and space against his will. This appears to be contradictory to Future Hiro's statement that he risked creating a "rift", as well as his existence being proof that he is trying to prevent the catastrophe.
Hiro's ability was stolen by Arthur Petrelli in 1991, who had time traveled back from 2007 using the same power gained by his son. Arthur died after his return to 2007; leaving present-day Hiro trapped in the past before he was rescued by Ando and Daphne.
Hiro claimed his trip to India was the key to regaining his lost powers, however, it turned out that his destiny was to be a hero without powers.
Hiro has regained his ability thanks to Matt Parkman Jr.'s ability. He used his restored time-stopping abilities to escape Danko's team as they were trying to capture him, Ando and the baby. During the escape, he tried to use the teleportation aspect of his ability, but could not. He later stated that he could not time travel. Hiro had also demonstrated that using his ability too much caused some kind of adverse effect. He had a terrible headache and his nose began to bleed after stopping time at least four times in less than five hours. Hiro also discovered the ability to keep others "unfrozen"with him by touching them as he freezes time. (I Am Sylar). Mohinder Suresh, after examining Hiro, said he thought that Hiro's body was rejecting his ability like a virus, and further use of it could be extremely dangerous. Hiro was diagnosed with a brain tumor that was causing him to die. He has since demonstrated the time travel and teleportation aspects of his ability accidentally. He did not possess control over these restored parts of his ability, using them just on reflex. Hiro said that destiny is doing this and that time and space are now the master of him. In addition to headaches and nosebleeds, Hiro also sometimes remained frozen in time while the rest of the world stays unfrozen. He also saw the past in this condition once, and then travelled there accidentally.
After a lot of effort, Hiro was able to time travel and teleport at will, but couldn't control it completely. He was able to teleport to the carnival with Samuel in anger, but later needed a couple of tries to get back to the right time to save Mohinder: the first time he tried he landed ten minutes too late but got it right the second time. He also seemed to have displayed at will teleportation as he trapped Mohinder in a mental hospital in Florida (Once Upon a Time in Texas, Brother's Keeper). After having his brain scrambled by Damian, Hiro was incapable of willfully using his powers. Once his mind was fixed by Ando, Hiro was instantly able to teleport at will with no apparent problems, taking Ando and Mohinder Suresh with him to Noah Bennet's apartment. This was also the first time since regaining his ability that he has taken more than one person with him.
After Hiro's brain tumor was removed, he regained full control over his powers and tested it out by rewinding time for himself by ten seconds. He is later able to teleport himself and Ando to the Carnival in Central Park with no problems or health issues. At the Carnival, Hiro is able to teleport all of the carnies an unknown distance despite there being dozens of them by having everyone hold hands with each other and Ando supercharging him at the same time, giving Hiro the boost he needed to teleport that many people.
Following his release from Evernow, Hiro was able to freeze time around Noah Bennet without being physically present or freezing Noah.
At the Odessa Peace Summit, Hiro freezes time to find out what will happen if he stops M. F. Harris bombing the summit. Hiro is shown teleporting within close proximity within seconds of each other before finally stopping and teleporting away for good. He later tells Noah that he discovered he can't change this event as there are too many bombs and has seen that any attempt to do so will result in a worse future, indicating that he is now able to reverse the changes he makes to the timeline. Hiro tells Noah that he can't change fate, even with his abilities.
After arriving in 1999, Hiro loses his powers for a second time to Tommy Clark. Even without his abilities, he was able to train Tommy in the use of them to the point that Tommy could send Noah through time and space without sending himself with Hiro's direction, indicating Hiro may have learned that aspect of his ability himself before losing it.