Big Hero 6 Wiki

While I do not wish... to harm anyone... you should know... Baymax... that few are the men who... have challenged... me and lived.

Sunfire (real name Shiro Yoshida) is a former member of the Big Hero 6, as well as a member of the X-Men in the past.

Possessing the ability to fly and generate super-heated blasts of plasma, Sunfire became one of Japan's most prominent heroes.


Shiro was born in Agarashima, Japan. He was raised by his uncle Tomo as a child after his mother died from radiation poisoning caused by the atomic bomb dropped on Hiroshima during World War II. As a result, Shiro was born a mutant possessing solar radiation abilities.

Because of Tomo, Shiro was influenced to hate Western civilization and sought to restore Japan's former glory—despite the fact that his father was an ambassador to the United Nations. He attacked the United States Capitol until the X-Men intervened. However, Sunfire witnessed Tomo killing his father, prompting Sunfire to kill Tomo in a change of attitude. For his actions, he surrendered to the authorities and returned to Japan. Months after the incident, Sunfire was recruited to rescue the original X-Men from Krakoa, the Living Island. However, he denied that his assistance constitutes his becoming a member of the X-Men.

During his time as a student, Sunfire also faced Dr. Kishi Oramosha, a brilliant businessman turned into a villain calling himself Deadline, who threatened the entire world with a machine called Doomsday Device, deciding to attack Japan first due to its lack of superheroes. Sunfire managed to defeat Oramosha, destroyed his machine, and had him arrested.

When Magneto released an electromagnetic pulse across the globe, the energy overloaded Sunfire's body and made his powers flare out of control directly over Tokyo. This forced the Japanese government to imprison Sunfire, but he was soon freed by his cousin, the Silver Samurai, and Wolverine to help oppose a government plan to outfit giant Red Ronin robots with mutant-hunting technology. Battling one of the robots, Sunfire's powers again flared out of control and Wolverine suggested he seek aid from Canada's Department H, unaware that the Department had fallen into malevolent hands.

Falsely informed by the Department H's scientists that he had radiation poisoning, Sunfire remained with them seeking a cure. Unknown to Sunfire, the scientists had injected him with Zero Fluid, a compound that created an ambient charge of bio-kinetic energy within his body that conflicted with his bio-atomic powers and gave him problems controlling them. They also lied to him by saying that his powers and the fluid had formed cancer throughout his body and that he would have to serve them in order to receive the necessary treatments.

Sunfire refused, and returned home instead, seeking refuge in an abandoned monastery.


Shiro can be very arrogant and temperamental at times, but greatly cares about his friends. He was a former nationalist but changed his views after his father's death.


Sunfire dons a mostly red-and-white costume representing the rising sun symbol of Japan.

With the Zero Fluid compound, half of his entire body turned jet-black and eventually engulfed all of his skin.

Powers and Abilities

  • Martial Arts: Sunfire is well versed in the martial arts of karate and kendo, as well as the art of bushido: the history and customs of the samurai class.
  • Heat Manipulation: Sunfire can biochemically ionize matter and convert it into the super-heated plasma state of matter, generating temperatures of about 1,000,000° Fahrenheit which he most often releases as force blasts from his hands. He can recharge and enhance his stored power by absorbing both solar and electromagnetic energy.
  • Infrared Vision: Sunfire can view his surroundings in the infrared spectrum.
  • Flight: Sunfire can create super-heated air currents that enable him to fly while leaving a trail of flame behind him.
  • Psionic Shield: Sunfire also generates an invisible field of psionic energy that protects him from the heat and radiation generated by his own powers, as well as from outside sources. The field also shields him from air friction and the light generated by his plasma, as well as lending a certain level of protection from kinetic impact.


When the Japanese organization known as the Giri Corporation began enlisting superhuman individuals to form a national superhero team known as the Big Hero 6, Sunfire was selected as a possible candidate, but after Sunfire's encounter with Department H, news were spread about him allegedly dying.

Young genius Hiro Takachiho mourned his "death" as Sunfire was his idol, but still, Hiro had hope and built a bio-atomic parcel detector specifically to be alerted if Sunfire ever returned. Though the technology was believed to be "impossible", it worked one night, so Hiro and his robot bodyguard Baymax went out to search for him.

They found Sunfire at the monastery where he was hiding, but the excited Hiro quickly became disillusioned to see his hero in the state he was, noticing that half of his body was covered with the Zero Fluid. As Sunfire told them to leave, once again his powers flared out of control, so Baymax's programming detected this as an attack and triggered his battle mode, fighting Sunfire despite him trying to explain it was an accident and Hiro attempting to stop Baymax. The fight was interrupted by the members of Big Hero 6 at the time: Silver Samurai, Honey Lemon and Go-Go Tomago, with Sunfire falling unconscious after the battle, while on the other hand Hiro and Baymax returned home.

Shiro was taken to the Giri headquarters and put under observation by scientists. Waking up, he saw Honey Lemon who stayed by his side telling him that he should be treated as a guest and not a lab rat. Shiro noticed the scientists looking at him from the other side of the window, causing him to angrily shoot flames to polarize the window and tell Honey Lemon that, after what happened with Department H, he no longer trusted any organization.

On the other hand, a mysterious entity calling himself Everwraith abducted Hiro's mother and blackmailed Hiro, telling the boy to bring Sunfire to him. Soon, Hiro and Baymax stormed the Giri building, but after explaining his situation, Mr. Oshima allowed Hiro to visit Sunfire, who had given up and simply laid in bed, waiting for his supposed death. Hiro decided to stop crying for him after remembering that he had gotten through his father's death already and instead turned to the rest of Big Hero 6 for help.

Big Hero 6 agreed to help, and so the team faced Everwraith, but were unable to defeat him due to his ghostly nature. Despite his condition, Sunfire arrived shortly after to help the team, unaware that he was the villain's real target all along. The Everwraith explained to him that he intended to use Sunfire's powers to cause an atomic explosion in Japan as it had been done in World War II, with the belief that the only way the nation could become stronger would be by creating another tragedy to overcome. Everwraith used his necroplasmic blasts to trap Shiro and siphon his powers, then redirect them at solar panels he had planted to engulf all of Tokyo with the flames.

As Baymax saved Hiro's mother, Go-Go tried destroying the panels, and Silver Samurai and Honey Lemon fought Everwraith, Hiro told Sunfire to use his bio-kinetic Zero Fluid to counter Everwraith's grip, but this confused him so Hiro explained that he thought the fluid was part of the "treatment" to cure him. This caused Sunfire to finally realize that he was being lied to all along and was never dying, and it was the Zero Fluid conflicting with his powers. Shiro then released all of the bio-kinetic energy to break free from Everwraith's control and redirected all of his flame power at the solar panels and Everwraith to incinerate them. This seemingly obliterated the ghost and Shiro's own body in the process, but the city and the rest of Big Hero 6 remained safe.

The next day, Shiro's teammates held a funeral for him, but Hiro stayed for longer at the temple to see him arrive, knowing all along that he had survived too. Sunfire tells Hiro that he has to leave to find answers, and both embrace a hug before Sunfire leaves the country headed to Canada.

Eventually, Sunfire arrives enraged and breaks into Department H, looking for the doctor who had experimented on him, though he reached a dead-end as he only found the Alpha Flight members telling him that the program he was part of had been terminated and there was nothing left of it. At the same time in Japan, Big Hero 6 had moved to a new base at the Cool World Amusement Park, where they were being attacked by a giant monster known as X the Unknowable. Although Big Hero 6 attempted to stop the monster, Hiro believed that only Sunfire could defeat it, so he revealed to the others that he still lived and asked Honey Lemon to call him even though Silver Samurai was hesitant about it, claiming that Sunfire had chosen his own path and it wasn't with Big Hero 6.

Regardless, Sunfire received the message and hurried back to Japan accompanied by Alpha Flight. Both teams helped clean the disaster at the park and chased the monster, then found out that a small boy named Tomi had brought X to life by writing a comic about it. Despite their efforts, all events happening were part of the comic's story, until Sunfire sunk the monster into Mount Fuji and saw a bizarre ending in which X resurfaced as a human and married a princess. Both teams decided it was best to just leave it be, so after X's "ending", Alpha Flight returned to Canada while Sunfire decided to stay with Big Hero 6 in Japan.

Following this, Big Hero 6 began to dismantle organized crime in Japan in order to clear the name of Silver Samurai's Clan Yashida.

Eventually, Sunfire and the Silver Samurai would depart from Big Hero 6 for good—the former leaving in order to work at the X-Corporation office in Mumbai, India; and the latter gone because he had lost control of Clan Yashida, causing him to go back to his criminal ways and having his death faked after facing Elektra Natchios.

Sunfire's spot on the team was filled by Lumina, a young woman of the Coronarian species with similar solar-based powers than him. Lumina took the mantle of "Sunpyre" in honor of Shiro's deceased sister, Leyu Yoshida, who was known by that alias. Silver Samurai was also replaced by Ebon Samurai, and with the two most experienced members of Big Hero 6 gone, Hiro became the team's new leader.


  • Sunfire, along with Silver Samurai, are the only founding Big Hero 6 members who are removed from the film incarnation, due to the company 20th Century Fox owning the film rights to the X-Men and related characters at the time of the movie's release.
    • Ironically, the founding members of the film's team are Wasabi and Fred, who were the last characters to join the team in the comics.