Ando is introduced into the show as the skeptic friend of Hiro Nakamura. He works at Yamagato Industries with Hiro, and when we first see him working, he is actually on Niki Sanders's strip website. When Hiro discovers his powers, Ando is completely skeptic, and doesn't believe Hiro has them.
Hiro continues to try and convince Ando that he has powers, but Ando still doesn't believe him. When the two go to a bar, Hiro tries to show Ando that he has powers by teleporting into the girls bathroom. Ando goes to get beer, and when he comes back, Hiro is being thrown out. Outside, the two argue, with Ando questioning why Hiro wants to be so different?
Ando is finally convinced that Hiro has powers when Hiro brings a comic book by Isaac Mendez from the future, and Hiro saves a girl with them. He then agrees to go on a trip with Hiro to America, following the comic book. They hire a Nissan Versa and head for Las Vagas. The two spend time at a casino, where Ando tells Hiro to use his powers to get them money, which he does but they get thrown out of the hotel. After attending another poker game, the two argue and seperate, and Ando goes to see Niki Sanders.
Ando later wanted to kill Sylar himself but failed and he was saved by Hiro Nakamura.He also took part at the Kirby Plaza showdown where the heroes faced the ultimate villain , Sylar but Hiro lost control of his power and was sent back to 1671 in the feudal Japan where he encountered his childhood hero, Takezo Kensei.
Four months later, Ando was having a talk with Hiro's father, Kaito Nakamura when Kaito got a letter which tells that he will die. Ando eventually got letters from Hiro via the Kensei Sword which contained hidden messages.Later he was helped by Matt Parkman but with no luck to find Hiro.
After Hiro returned from the past few weeks later he went to face Adam Monroe who killed his father and was also Takezo Kensei four thousand years ago.
When Hiro travels to the future, he sees himself and Future Ando confronting each other on the a stairway, with Ando demanding the one half of the formula that Hiro has acquired. When Hiro pulls out his sword and attacks, Future Ando blasts Hiro with a bolt of lightning, immobilizing him. Future Ando takes the formula, and moves on. After returning in the present,
Hiro began avoiding Ando so he can move on with what he saw in the future.Eventually the formula is put together and Ando injects himself with it so he can save Hiro who previously trapped in the past after Arthur Petrelli took his ability.Ando manifested the ability of supercharging and with Daphne's ability they could bring Hiro Nakamura back to the present.
Four weeks later Hiro began living 'through' Ando becuse he lost his ability of space-time manipulation and wanted to help someone.Ando compared their relationship as Bruce Wayne and Dick Grayson who are Batman and Robin.
They went to save baby Matt Parkman from the governements army and they succeded and with the baby's ability, Hiro got his power back but later manifested head aches,bleedings and eventually was diagnosted with brain tumor.
Six weeks later Hiro Nakamura and Ando Masahashi started their own business called 'Dial a Hero' but they were no customers.After Hiro teleported accidentaly back to a carnival fourteen years he changed the past by 'stepping on the right butterflies' and thanks to him, Ando and Kimiko Nakamura fell in love and they decided to marry.
Hiro's brain tumor got worse and began talking nonsense until Hiro figured out that all of this is a hidden message. Arkham Asylum is actually a sanatorium and Dr.Watson whom Hiro was talking about is actually Mohinder Suresh and they broke him out and with Ando's ability, they 'healed' Hiro's brain but he fell in coma after that.Soon Hiro was operated and Ando went to see him and the two began talking.
Close to You
As part of their plan to save "Watson", a reluctant Ando checks Hiro into the mental hospital "Watson" is trapped in. Ando isn't allowed to follow Hiro through a set of doors, but Hiro finds "Watson's" room and points it out to Ando. Ando shocks a keypad, allowing him to bypass the lock and he realizes that he's there to rescue Mohinder Suresh when he looks into the room and sees Mohinder.
Ando later visits with Hiro and asks why Mohinder doesn't use his powers to get away and Hiro makes him realize its because Mohinder is drugged. Seeing an opportunity, Ando switches Mohinder's pills with aspirin when an orderly isn't looking, but accidentally swallows Mohinder's pills and ends up drugged. Hiro leaves him in a closet and is able to free Mohinder thanks to Ando's efforts with the pills, but when they returns to Ando, he is in an extremely drugged state and his hands are glowing with his power.
The two wheel him out in a wheelchair, but are caught by orderlies. Snapping out of his daze, Ando blasts a door out open, creating enough of a distraction for Mohinder to overpower the orderlies. The three try to escape through a swamp, but are chased by orderlies with dogs and Hiro can't teleport them to safety due to his condition. Mohinder, after getting an explanation from Ando, suggests that Ando use his power like electro-shock therapy to try to return Hiro to normal so he can teleport. Ando is reluctant as his future self killed Future Hiro with that power, but Mohinder convinces him as they're in Florida and his future self was in Japan. Ando shocks Hiro, successfully restoring him to normal. In the nick of time, Hiro teleports himself, Ando and Mohinder away, just as dogs and orderlies find where they were hiding. The teleport takes them to Noah Bennet's apartment where they interrupt him and Lauren Gilmore kissing and Hiro asks for their help.
In Noah's apartment, Ando notices that Hiro is not looking so well. When Mohinder leaves and Hiro collapses, Ando rushes him to the emergency room and informs the doctors that Hiro has a brain tumor. He then watches as they take his unconscious body.
Meanwhile, in Hiro's dream, Ando is summoned to be Hiro's lawyer. Ando comments that things do not look good and says that things will work out. Adam Monroe calls younger versions of Ando and Kimiko to the stand and the kids tell the court how Hiro changed time so that they fell in love. Older Ando argues that what Hiro did was good and that no one was hurt. Later, after Sylar has spoken, Ando calls Hiro to the stand and asks what he has to say about it. Hiro tells everyone that he tried to be a hero and make the world a better place but Kaitosentences him to death. Later, Ando is amongst those who encourage Hiro to fight for his life. In reality, having watched the operation on Hiro, Ando is overjoyed when his friend survives the surgery and the tumor is succesfully removed.
Brave New World
Ando is in Hiro's hospital room and is happy when Hiro wakes up. He asks Hiro if he has full control of his powers back now that the brain tumor is gone and Hiro tests them by rewinding time by a minute, proving that he does. Ando and Hiro are confused when Hiro receives a note from another patient and are shocked to discover that it is a now-old Charlie. Ando witnesses Hiro's reunion with Charlie, but is unhappy with Hiro's decision to go back in time and return Charlie to her own time after she's taken as Charlie clearly has had a good life. Ando receives a phone call from Noah Bennet telling him that the Carnival is in Central Park and he and Hiro need to get there right away. Ando approaches Hiro who is saddened as he has decided not to return Charlie to her own time and believes all of his missions are now over. Ando reminds him about Samuel and tells Hiro that the Carnival is in Central Park and that "destiny calls". Hiro agrees and after blowing Charlie a kiss goodbye, teleports himself and Ando to the Carnival as Charlie watches. At the Carnival, Hiro and Ando are approached by Noah, Claire and the carnies and Claire asks Hiro to teleport the carnies away. Hiro has the carnies all hold hands, but confides to Ando that he's not sure he can teleport everyone as there are dozens of carnies. Ando offers to supercharge Hiro's powers to give him the boost he needs and Hiro agrees. With Ando supercharging him, Hiro is able to teleport everyone away from the Carnival, rendering Samuel practically powerless without other specials to draw power from and allowing Peter to defeat him. Hiro and Ando later walk through the nearly empty Carnival and decide to go home before watching Claire reveal her powers to the world.
During the first two volumes, Ando is a normal human with no abilities. In the opening episode of the third season, " The Second Coming", Hiro Nakamura travels into the future and witnesses Ando using an ability described by the writers simply as "red lightning". In " Dual", Ando injects himself with the formula, revealing that the red lightning amplifies the abilities of others. He demonstrates this unintentionally by boosting the range of Matt Parkman's telepathy to cover all of New York City and increasing Daphne Millbrook's super speed to such an extent that she is able to break the spacetime barrier. In the episode "Cold Snap ", Ando learns to use his power offensively, channeling his energy into powerful bolts from his hands after having contact with Baby Matt Parkman. As seen later in "I Am Sylar", Ando has managed to produce and control a major amount of energy as he attacks agents inside a van with a heavy blast without damaging Hiro or the van itself.
Ando obtained the ability to supercharge others' abilities, which manifests in the form of red energy resembling electricity. He used it to greatly amplify Matt's telepathy, allowing him to hear the thoughts of all New Yorkers, and Daphne's super speed, allowing her to run faster than light and travel backward in time (Dual). He is also able to use this to supercharge Hiro'sspace-time manipulation, allowing him to teleport dozens of people an unknown distance all at once. (Brave New World)
In the episode Cold Snap, it is shown that Ando can charge the red energy in the palm of his hand and expel it as a concussive blast outwards. The energy is shown to be strong enough to knock a man, fully geared, backwards several feet. It cannot be discharged quickly, however, as it seems Ando requires at least a small amount of time to build up power. However, as of I Am Sylar, Ando's use of this has increased: he is able to blast all of Danko's team in a van with one shot, knocking them out but not taking out Hiro at the same time.
Ando is later able to shock a keypad, causing it to act like the proper code had been put in and not short out and later blasts open a door with his ability to shoot energy blasts from his hands. Later, Ando, at Mohinder's suggestion, uses his power like electro-shock therapy in an attempt to restore Hiro's scrambled brains back to normal and it works, reversing the effects of what was done to Hiro. (Close to You)