Rengoku is a Demon Slayer of the Demon Slayer Corps and the Flame Hashira. He is enthusiastic in regard to his duties as a Hashira, and often came across as cheerfully eccentric. He is amiable, pure of heart, and boasted extraordinary technique and swordsmanship stemming from strict practice and discipline. Rengoku is an honorable warrior who adhered to his code of morals and principles; the most significant being his belief that those who were born strong have a duty to protect the weak.