Demon: Slayer- Kimetsu No Yaiba - Infinity Castle

Throughout the arc, the protagonists face numerous challenges and adversaries within the castle walls, including powerful demons and Muzan's elite warriors, the Twelve Kizuki. The Infinity Castle serves as a catalyst for Tanjiro's growth and development as a demon slayer, as he confronts the darkness within himself and the true nature of the world he lives in.