Tanjiro documents his training in a journal for Nezuko, who has yet to wake from her two-year slumber. He’s learned that the Demon Slayer Corps, which has several hundred people, is not government-affiliated but has existed since ancient times. Demons have combative and regenerative powers; they eat humans and can only be killed by sunlight or with a special sword. Demon slayers are trained protectors of humankind who are sometimes equipped with special abilities. Urokodaki is a trainer for the Demon Slayer Corps. As Tanjiro’s trainer, he’ll decide if Tanjiro can face the final selection for entry into the Demon Slayer Corps, atop Mount Fujikasane.

Tanjiro’s mountain training makes him stronger, faster, and better at sniffing out traps. Urokodaki teaches him how to wield katanas, how to fall and get up quickly, and how to control his breathing. Tanjiro trains this way for a year; Nezuko sleeps the entire time and Tanjiro is fearful he’ll wake to find her dead. After a year, Urokodaki tells him that he has nothing left to teach him, and if Tanjiro can break a large boulder, he’ll let him face the final selection. For six months, he tries fruitlessly to break the boulder.