Demon Slayer season 3 is set to be released on Sunday, April 9, 2023, at 11.15 pm JST. There is massive hype around season 3, with fans excited to learn more about the Upper Rank Demons that will feature this season. Moreover, the group of demons meeting in Muzan's Infinity Castle has also peaked fans' interest.
In the Demon Slayer Swordsmith Village movie, fans were given a taste of the first episode of season 3 which showed all the Upper Rank Demons assembling in the Infinity Castle after the deaths of Upper Rank Six: Daki and Gyutaro. We also got to meet Nakime in the movie, who was shown to be a resident of the castle.
Demon Slayer: Infinity Castle is the Blood Demon Art and domain of Biwa Demon Nakime
Demon Slayer's Infinity Castle is shrouded in mystery, appearing only a handful of times in the anime. This extra-dimensional castle is Biwa Demon Nakime's Blood Demon Art. She has total control over the castle and can manipulate its space at will. By strumming her Biwa, Nakime is capable of manipulating the entire space, changing the layout of the entire castle.
She sits at the center of the Infinity Castle playing her Biwa, controlling everything around her. The castle has endless rooms which are all interchangeable and even helps Nakime counter offensively against enemies. The castle plays a huge role in the Infinity Castle Arc, which is the first part of the Final Battle Arc.
This arc follows the Demon Slayer Corps raiding the castle in order to kill Muzan once and for all.
In regards to anime, the castle has been used by Muzan Kibutsuji to meet with his demon underlings. However, due to the Lower Rank Demons consistently losing to Hashira, they have lost the favor of Muzan and are said to be even unaware of the castle's existence. The Lower Ranks got to visit the castle only once in the anime, at which point Muzan decided to exterminate them all, with the exception of Lower Rank One: Enmu.
The Infinity Castle is mainly used by Muzan to meet with the Upper Rank Demons. The demons are summoned to the castle by Nakime through the use of her biwa, at the will of Muzan. In the Demon Slayer Swordsmith Village movie, we saw the remaining Upper Rank Demons being summoned to the Infinity Castle following the deaths of Upper Rank Six: Daki and Gyutaro.
Muzan summoned them to the castle to devise a new plan of action and to express his disappointment in them. We also get to see Upper Rank One: Kokushibo make an appearance along with two main antagonists of the upcoming season 3, Upper Rank Four and Five: Hantengu and Gyokko.
It'll be interesting to see the two demons fight against Mist Hashira Muichiro Tokito and Love Hashira Mitsuri Kanroji in the upcoming season along with protagonists such as Tanjiro and Genya. Infinity Castle will once again be featured in episode 1 of season 3 and will play a significant role in kickstarting the new season.