|A young Akugata expert and Confrontation Beast-Lion Fist artist. He was just a child when his entire family was murdered by a monster during a thunderstorm. Since that event, Rio sought to be stronger. He was discovered by Master ShaFu and was raised by him. Now he is his rival. He defected to the RinJyuKen Akugata's allure of great power. Setting up a dojo on a towering isolated mountain as his base of operations, he brought many warriors back from the dead along with the ancient Akugata history, forming the Confrontation Beast Hall. He causes despair and sadness in humanity. When Rio mediates, he falls asleep and relives the horrible traumtic childhood event. At the beginning of the series, Rio sought to revive the Kenma (Three Fist Demons), creators of the RinJyuKen. Makirika stole the Fist Demon Bracelets for Rio. He called forth the Five Venom Fists to obtain Braco's hidden Rinki, the True Poison, to revive the Fist Demons.
With the "Rinki Triumphant Armor" Ringi, Rio first debuted this black and gold armor in episode 4. His ultimate attack is 'Brave Roaring Waves,' projecting his Rinki as a lion fiercely attack the opponent with its strength. This lion later becomes a RinBeast, first seen in the Movie and then in Episode 33. His other attacks include the Splitting Kick, Splitting Fist, Thunder Hard Bullet, Brave Strike and Lion's Roar Wave, a stronger form of the Brave Roaring Waves.
He finally got hold of three of the remaining True Poisons from his loyal servant Mele, a Rinrinshi he half-resurrected. He chose her because he saw she sought strength much like him. She loves him. and when Rio obtained True Poison, Kata the Sky Fist Demon told him where to find his corpse to revive it. He tested Kata to see if he is worth to be his master. Once he is Kata's pupil, Kata pushes him to the test by reliving his dark past and almost dies in the process. Rio eats his own fear, which surprises Kata. As he continues on his dark journey, Mele worries about him. When Mele brings Rageku, Rio wants to learn from her but she isn't impressed and wants to train Mele. She infects Rio with a venom, that when he uses his Rinki, the venom will spread faster. Mele is forced to fight ShaFu and fights him to the point of exhaustion. Rio broked the venom curse and stopped Mele from using her third attack towards ShaFu. He then proved himself in battle to Rageku, who believes Rio was jealous of Mele becoming stronger than him. Rio and Mele both became her students.
Rageku believes in letting whoever angers you burn your body and using that passion as your power. Rio thought it was a waste because he no longer envied ShaFu and didn't believe anyone could supass him. Rageku made him dig deep and think about who really angered him. He mentioned Byakko, a white tiger, one that with whatever he did, he could not defeat him. Rio underwent a RinMei Ceremony to prove his commitment in Episode 19. He beat up the Gekiranger twice and was then severely injured by the Super Gekiranger. He tried to revive the last Kenma and successfully did with the Ikigimo Mele retrieved. Rio wanted to obtain Maku's Dorinki (Fury Confrontation Ki) but it was easier said than done. Maku took Rio's place as the leader of the Confrontation Beast Hall, because he is the originator of RinJyuKen. Rio managed to obtain the DoRinki and sought to overthrow Maku. Mele stole the SouJyuTo from Ken and with that, she and Rio went to Sacred Ground for more power. When they reached SaiDain, that contained the soul of the creator of JyuKen, Rageku sent Rio, Mele and the Gekiranger into the Edo Period. Because of the pressures of time travel, Rio lost his memory and the SouJyuTo was stolen by a disciple of Rageku. Mele played house with Rio until Ron came and restored his memory. He worked alongside the Gekiranger to form GekiRinTouja to retrieve the SouJyuTo. When they returned to their rightful time period, Ken released SaiDain and it conducted the Blooming Beast Power, which powered up Rio and Mele. Rio, with a new surge of power, told Jan to kill Maku, so the old GekiRin Rebellion would end and they could continue their own rivalry.
When the Gekiranger indeed killed Maku, Ron revealed himself to Rio and intrigued him with the lessons of GenJyuKen, promising more power. But he was not so easily persuaded until Ron awoke Suugu, whom Rio recognized as Dan. Soon after, Rio undergoes the Blood-Oath Ceremony, embracing his destiny and gaining a new fighting form, Phantom Beast King Rio, that gives him mastery over the Phantom-Beast Gryphon-Fist style. Rio then revealed to everyone that he killed Dan, using his Rinki for the first time and his GekiSoul was used to make Suugu. Back then, Rio was insulted that Dan went into battle even though he was wounded eariler. It was later revealed that Ron was the one who soften him up for Rio. After discovering he was merely a pawn and the GenJyuOu form was mearly to control him, Rio shed off his GenJyuKen form and became the Black Lion once again. Rio couldn't believe Ron was the mastermind, as he saw him more as an underling. Ron, the one responsible for murdering his family and was using him, couldn't figure what was still tying Rio to his humanity because, he wanted to strip Rio of it all. But once Rio took a blow meant for Mele, Ron realized it was Mele who was still teathered him down.
After Ron was defeated by the SaiDaiGekiRinTouja, Rio and Mele then went to SCRTC. Gou, Miki and Jan very happy to have Rio back. But, not Ran and Retsu, who can't forgive them for their sins. So Rio decides to undergo the Fist Judgement to cleanse himself of his sins, knowing full well that his life may be sacrificed in the process. To symbolize the end of the RinJyuKen, Rio burns the Confrontation Beast Hall to the ground. He takes on Retsu in the Fist Judgement, fully intending to sacrifice himself. Ron interrupt the proceedings and assumes his true form, bent on destroying everything. After Mele's selfless sacrifice, Rio takes a small remnant of her remains into himself and decides to eliminate Ron, despite Jan's protests. As a final act, he gives the Gekirangers the last remaining Rinki that was given to him by the Kenma as penance for his deeds, and sacrifices himself in order to stop Ron's rampage. Upon arriving in the afterlife, he is met by Mele and the two walk off, hand in hand. In Episode 49, both Rio and Mele guide the three Gekirangers into the RinJyuDen and reveal the Fist Demons, in human form, before them, showing the path to unifying the two JyuKen schools.