His older sister died when we was young by a demon. When he was a teenager, his best friend, Sabito, was killed during the demon slayers Final Selection by a demon because he was protecting Giyuu from the demon. Giyuu carries the guilt of his sister and best friend's death with him still to this day. He believes that he doesn't deserve to be a Hashira and he hates himself. He doesn't think he is good enough for anything. He has depression, survivor's guilt, and inferiority complex.