Kyojuro Rengoku was an exceptionally strong Hashira (Pillar) of the Demon Slayer Corps, considered among the top fighters in the series. He had immense physical strength, speed reaching hypersonic plus levels, incredible endurance, and stamina. Rengoku was able to hold his own and even match strength with the Upper Rank Three demon Akaza, demonstrating outstanding combat skills, rapid regeneration, and indomitable will despite severe injuries. He used advanced Flame Breathing techniques, including a powerful Ninth Form attack causing massive explosions. Many analyses rank him as the seventh strongest Hashira, stronger than some others like Tengen and Shinobu. However, it is generally agreed that he could not singlehandedly defeat Upper Moon demons, who represent the highest threat level. Rengoku's strength, intelligence, and masterful swordsmanship made him a formidable force and an inspiring figure within the Demon Slayer Corps.