Sumikko Rengoku

Sumikko was born on December 22nd 1900 of the Taisho era. When she was just an infant her parents were murdered by the Upper Moon 3 Akaza one of Muzan's minions, she was found and rescued by Kyojuro Rengoku the flame Hashira then later on adopted her as her older brother and guardian. During her childhood she lived amongst the Demon slayer corp and looked up to Rengoku who was strong and compassionate. As she grew up she mastered the art of ice breathing a technique that can freeze your opponent and slash through tough skin. She had trouble learning the water breathing technique so instead she lowered her body temperature and pulse by combining Total concentration breathing and passed the final selection. During her mission she came across Tanjiro who rescued her when she was injured and together along with Zenitsu, Inosuke and Nezuko work together to defeat Muzan.