Voir Demon Slayer: Kimetsu no Yaiba (Original Japanese Version), Season 1 - Episode 4

To pass Final Selection, one must survive for seven days on Mt. Fujikasane, where demons captured by the Demon Slayers have been imprisoned. So begins the battle for survival between the young swordsmen and the demons. Armed with the breathing techniques and stances he learned from Sakonji Urokodaki, Tanjiro cuts through demon after demon. His two years of training have not gone to waste. But just then, a morphed demon appears out of nowhere.