Rengoku has yellow hair with fiery streaks and is a tall, muscular man. He wields a Nichirin katana and uses his flame breathing styles. He wears a kimono with flame patterns and has fiery eyes. Rengoku is a loud, friendly and determined individual, whose confidence never wanes even in the face of death. He may seem simple, but he is logical and quick to act in battle. He enjoys sweet potatoes and works to defeat as many demons as possible. He is one of the Hashira, being the flame Hashira.