Over the next year and a half, Tanjiro trains with Urokodaki, improving his physical form and learning how to use a special breathing technique Total Concentration, to accelerate his stamina and speed. One day, Urokodaki declares that if Tanjiro can slice a boulder with his sword he will let him enter Final Selection — a survival test administered by the Demon Slayer Corps that will determine who can become a demon hunter. Tanjiro tries for the next 6 months, failing each time, while Nezuko continues to sleep. Worry over Nezuko and his continued failures push Tanjiro to the brink of giving up, until he is confronted by two children with fox masks, Sabito and Makomo...