Kyojuro Rengoku was one of the nine Hashira, a group of the nine greatest Demon Slayers in the Demon Slayer Corps. Specifically, Kyojuro was the Flame Hashira who made use of the Flame Breathing. While not having his life being directly affected by Demons like many other members in the Corps, Kyojuro household had produced Demon hunters for generations. Kyojuro, with his sense of duty instilled by his ailing mother since childhood, saw it as a duty to protect the innocent from Demons and entered the corps to serve humanity.