Infinity Castle Arc

The Infinity Castle Arc is the first half of the overarching Final Battle Arc, and the eleventh arc of Kimetsu no Yaiba.

Synopsis
The Hashira rush to the Ubuyashiki Estate and Sanemi is the first one to see the mansion, and he feels relieved, believing that he will make it just in time. However, the mansion suddenly blows up in a huge explosion, with all the nearby Demon Slayers witnessing it in shock. Even Muzan, with his skin burned off, and his left eyeball entirely exposed, is surprised at this as Kagaya had looked calm – with a serene smile, as he, along with his family blew themselves up.

In order to delay Muzan's regeneration, he made the explosion deadlier by adding spike traps and while Muzan was busy trying to heal himself, he was again attacked and immobilized by a Blood Demon Art which summoned spikes in the area. Due to the spikes piercing his flesh, Muzan tried to absorb them to escape but out of nowhere, Tamayo appears and stabs Muzan with a special medicine she had concocted. However, Muzan absorbs her entire arm as she does so.

Suddenly, Gyomei Himejima arrives and cleaves Muzan's head clean off, though the Demon is able to regenerate. Soon the other Hashira also arrive and Gyomei tells them that the one he is fighting is Muzan and that he will not die even if his head is cut off. The Hashira, given that it was their first time seeing him, were shocked at first but proceeded to attack him with their respective Breathing Styles – including Tanjiro Kamado who was with Giyu Tomioka when the explosion occurred. They attack Muzan from all sides but before they are able to land even a single blow, they are transported into the Infinity Castle and are separated.

While falling, Muzan mocks the Demon Slayers and proclaims that he will slaughter them all that night. Tanjiro rebuts that it would be Muzan who would be going to hell that night and that he will defeat him. Muzan dares Tanjiro to come and get him if he can as the Demon Slayers' decisive battle against Muzan and his forces is about to commence.

Battles

 * Demon Slayers vs Muzan Kibutsuji: Part 1
 * Shinobu Kocho vs Doma
 * Zenitsu Agatsuma vs Kaigaku
 * Tanjiro Kamado and Giyu Tomioka vs Akaza
 * Kanao Tsuyuri and Inosuke Hashibira vs Doma
 * Mitsuri Kanroji and Obanai Iguro vs Nakime
 * Muichiro Tokito, Genya Shinazugawa, Sanemi Shinazugawa and Gyomei Himejima vs Kokushibo