|Novel||Kakashi Hiden: Lightning in the Icy Sky|
Rahyō and his younger sister, Kahyō, were once shinobi of Kirigakure but fled the village in hope of a better life. After his nephew, Hakuhyō, died during the Fourth Shinobi World War, Rahyō helped found the Ryūha Armament Alliance in the hopes of creating a world where deaths like Hakuhyō's wouldn't happen anymore.
Initially, Rahyō was a cold man, easily willing to sacrifice innocent people for his cause, like executing them as a method to put pressure on Tsunade or use them as living bombs after promising to let them free. He even enjoyed the prospect of a young boy's death that somehow resembled the situation leading to the death of his nephew Hakuhyō, calling it a "form of retribution". During battle, Rahyō was confident in his abilities, even when fighting prominent enemies like Kakashi Hatake or Might Guy. However, he quickly got enraged when his enemies would behave in an unorthodox way during the fight, impairing the aim of his attacks. Despite his short temper, Rahyō could keep a calm head when the situation required him to. Moments before his death, he expressed surprise by Kakashi's attempts to save him and seemed to have a change of heart in his last moment, asking him if empathic shinobi like Kakashi really existed with a soft expression.
Rahyō was a man with a large build who wore a beard. His attire consisted of deep blue clothing and a chain mail. Under his overcoat, he had a sword concealed.
Rahyō was a formidable fighter, able to hold his own against Kakashi and Guy on several occasions, although said shinobi were most of the time handicapped either by the situation or by physical impairments.
Rahyō was a sturdy man, surviving a Leaf Drop to the head that pushed him through the floor without any repercussions. He was skilled in taijutsu, able to match Guy in speed and strength, although it should be noted that Guy was physically impaired during the fights. Rahyō's fighting style resolved around the usage of his kekkei genkai during close-range combat, boosting the impact of his attacks.
Rahyō was able to use the Ice Release kekkei genkai by simultaneously combining Water Release and Wind Release. By doing so, he could surround his fists with ice to augment the striking power or as a mean of defence.
Kakashi Hiden: Lightning in the Icy Sky
Main article: Kakashi Hiden: Lightning in the Icy Sky After the leader of the Ryūha Armament Alliance, Garyō, is imprisoned in the Blood Prison, Rahyō leads the Armament Alliance's forces in trying to secure his release. They first hijack the Tobishachimaru, a top-secret airborne ship sponsored by the Land of Waves and Konohagakure. They take the ship's passengers hostage and Rahyō sends their demands to the Fifth Hokage: release Garyō or he will kill one hostage every ten minutes. When one of the Konoha ninja providing ship security, Kakashi Hatake, begins neutralizing members of the Armament Alliance, Rahyō kills two hostages and threatens to kill more unless Kakashi surrenders. Kakashi does so, but Rahyō still executes a hostage after the ten minute time limit passes.
An explosion rocks the Tobishachimaru. Kahyō stabilizes the ship and Rahyō demands an explanation from Kakashi. Rahyō is quickly attacked by another Konoha-nin: Might Guy. Using his ice, Rahyō fights Guy's kicks, Sōshūga, and motion sickness. Kahyō, meanwhile, fights Kakashi, who has escaped from his restraints. But as she fights Kakashi, Kahyō's Ice Release: Earthen Consecutive Chains of Ice starts consuming the ship and threatens to destroy it. Rahyō tells her to stop, but when she doesn't listen he is forced to knock her out. Her ice disappears, causing Guy and Kakashi to be sucked out of the ship. Afterwards, the Hokage contacts Rahyō and informs him that the Third Tsuchikage has vowed to destroy the Tobishachimaru and everyone on board unless the hijacking is ended, but Rahyō is not deterred.
One of the passengers pleads with Rahyō to release her son, whose asthma is acting up and has lost his medicine in the hijacking. Rahyō contemplates allowing the boy to die, payback for the death of Hakuhyō. Rahyō is confronted by Kakashi, who was rescued from his fall and returned to the Tobishachimaru by Sai. Kakashi offers to have Sai evacuate the boy. Frustrated by his return, Rahyō threatens to kill Sai and begins fighting Kakashi, but Kakashi is quickly captured by Kahyō. She also overrides Rahyō and allows the boy and his mother to leave with Sai. Kakashi is taken away.
Rahyō does not really believe that Konoha will release Garyō and only made the demand to buy time. Instead, he's had the Tobishachimaru flown to Blood Prison in Kusagakure. As they get closer, he equips the hostages with parachutes that have blue fire powder hidden within. As passengers disembark and pass through the clouds over the Blood Prison, the fire powder will be primed and detonate when they reach land, punching holes in the Blood Prison's walls that will give Garyō a chance to escape. Kakashi, who has escaped his restraints again, guesses that this is Rahyō's plan and demands that he stop.
Rahyō and the other Armament Alliance members begin throwing passengers overboard so that Kakashi can't stop them. But Kahyō, who was not informed of this part of the plan, is aghast. Rahyō tries to assure her that it's the only way to free Garyō, but Kahyō has now grown disillusioned. The Tobishachimaru experiences some minor turbulence, causing the remaining blue fire powder to detonate. Rahyō falls through the collapsing floor, but is saved by Kakashi. Rahyō is surprised, as he cannot understand why Kakashi would save him. Kakashi explains that, although he disagrees with Rahyō's methods, he supports Rahyō's desire to change the world, which Rahyō can't do if he's dead. The Tobishachimaru heaves and Rahyō is flung from Kakashi's grasp. As Kahyō cries out, Rahyō shouts his wish to have met someone like Kakashi sooner.