Hero of Hokkaido
Renji mentioned hardly looking like a student. He is 236 centimeters tall, half as broad and weighs 370 kilograms. He also is sporting a beard.
Renji is a nonchalant person, who doesn't take people who are weaker than him seriously. He also has great respect for agriculture.
During his youth, Renji was a rival of Ouma Kurogane, though the exacts of their relationship are unknown. Renji was never able to beat Ouma, but beating him fueled him to become stronger. Renji got up all the way to the quarter-finals of the 61st Seven Stars Sword Art Festival. Also, according to an urban legend, Renji had cleared over 100 hectares - equivalent to the Tokyo Dome - worth of land for cultivation, by himself, in his elementary school days.
Renji made an appearance in the party arranged to the participants of the Seven Stars Sword Art Festival. He met with Ikki Kurogane and Yui Tatara, and also ate Yui's poisoned chicken meant for Ikki. Despite Yui claiming it could kill an elephant, Renji remarked that it couldn't kill him.
Seven Stars Sword Art Festival Third Round - Beginning
Renji, having passed the previous two rounds of the Seven Stars Sword Art Festival, battled Akatsuki member Ouma Kurogane. Renji unveiled his device and turned into his new Tekkai · Ashurazou, which he had prepared specifically to face Ouma, his old rival. He attacked Ouma with hundreds of attacks, but they had no effect on the extremely durable Ouma. Ouma then cut off Renji's arms and pierces his chest, while also ripping out his heart, leading to Renji's elimination from the Festival. Despite the grave injuries, Renji survived, thanks to Kurono Shinguuji, who froze his body in time, allowing for him to be healed.
Renji is one of the people that helps Ikki train for the finals of the Festival. Renji attempts to catch Ikki off guard, with a surprise attack, but Ikki manages to block his attack and defeat Renji.
Expert Hand-to-Hand Combat: Renji's preferred form of fighting is hand-to-hand combat, and he is very skilled in this form of combat. His fighting style is based on sumo wrestling.
Immense Strength: Renji has an immense amount of physical power, enough to bring down entire dom which has around 300 meters on twenty centimeters down with a single stoop. Despite this he was still unable to damage Ouma, so his strength has a limit.
Great Endurance: Renji was capable of eating a poisoned chicken, that was claimed to have poison strong enough to be able to kill an elephant. He also survives after Ouma crushed his heart although he was saved by Kurono.
Steel Skin: Renji's ability as a Blazer, which allows him to turn his skin into steel.
Raiden: Renji's Device takes the form of a loincloth. It's usually hidden under his clothes.
- Tekkai Henge (lit. "Iron Mass Transformation"): Renji turns his skin completely into steel, covering his entire body. This enhances his attack power and durability.
- Tekkai · Ashurazou (lit. "Iron Mass · Asura Form"): An enhanced technique, where Renji uses his steel skin to create completely new arms. This enhances his attack output and defensive capabilities greatly.
- Ashura Hyakkashou (lit. "Asura Hundred Lotus Palms"): While in his Asura form, Renji attacks the opponent with hundreds of slaps, inflicting heavy damage. It's mentioned being a sure-kill technique, though Ouma was capable of withstanding it, without a scratch.
- Tekkoudan (lit. "Armor-Piercing Bullet"): Renji covers his palm in iron and hits his opponent with a powerful blow.
- Renji's Device, Raiden, is named after a Japanese god of lightning and thunder.