Tokitou Muichirou is a Demon Slayer and the Mist Pillar of the Demon Killing Corps. He is usually cold but has a soft side for people that reminds him of his family. Two months after joining the Demon Slayer Corps, he was appointed a Pillar of the Mist, making him the youngest Pillar of that era. Muichiro's past is quite mysterious, as he has a poor memory and seems to remember nothing of his past.

In the Swordsmith Village arc, while fighting against Upper Moon 5, Gyokko, Muichiro regained his memories, which triggered him to awaken his Demon Slayer Mark. This made Muichiro the first Pillar to successfully activate his Demon Slayer Mark.