Rengoku Kyojuro was a major supporting character of Demon Slayer Kimetsu no Yaiba and a major character in the Mugen Train Arc. Rengoku was greatly enthusiastic in regard to his duties as a Hashira, and often came across as cheerfully eccentric. While completing his last mission, Rengoku badly injured by to Akaza, the Upper Rank Three demon, while trying defeating him. Although he protected everyone on the Mugen train, he lost his eye and had permanent scars from the battle with Akaza.