Demon Slayer: Infinity Castle movie reveals the origin of Tanjiro's mark

The first Demon Slayer: Infinity Castle movie has resolved a decade-old mystery surrounding Tanjiro's Demon Slayer mark. Tanjiro's mark, initially thought to be a predestined sign, is revealed to be awakened through his father's teachings of the "Selfless State" combat technique. This technique is passed down through generations. This revelation suggests other Demon Slayers, particularly the Hashira, may also develop their marks by understanding this technique, hinting at future power-ups for the characters.