(SPOKEN IN JAP, SUBTITLED ENGLISH) The first instalment of the Infinity Castle Arc series follows the Demon Slayer Corps as they plunge into the Infinity Casle to defeat Muzan, the first demon. The arc sees the Hashira, including Tanjiro and his allies, battling the remaining Upper Rank demons, including Doma and Akaza, while navigating the shifting rooms of Muzan's lair.