Muichiro is the youngest hashira and became after 4 months of joining the demon slayer core. When he was younger his mother was sick and his father went to go get herbs for her during a storm. His father fell of a cliff and his mother succumbed to her illness. Muichiro only had his twin brother, Yuichiro left. Unfortunately a demon attacked their home and Yuichiro passed away from his injuries, Muichiro was also quite injured but he survived. Muichiro is Kokushibo’s descendent.