Demon Slayer: Kimetsu no Yaiba – The Movie: Infinity Castle (2025)

After recovering from Kagaya Ubuyashiki's trap and subduing Tamayo, Muzan Kibutsuji retreats into his dimensional stronghold, the Infinity Castle, and traps the Demon Slayer Corps inside. The Demon Slayers are separated and face hordes of Lower Rank-level demons as they search for Muzan and Tamayo. Kagaya's son, Kiriya, and daughters, Kuina and Kanata, lead the operation by mapping the Infinity Castle with the Kasugai crows and locating its inhabitants, with former Hashiras Tengen Uzui and Shinjuro Rengoku standing guard.

Shinobu Kocho encounters Upper Rank Two Doma, recognizing him as her sister Kanae's killer. Despite her use of poisons, Doma develops immunity to her attacks, ultimately killing and consuming her. Shinobu's adoptive younger sister Kanao Tsuyuri arrives too late to save her and takes her place in the battle against Doma, while the Kasugai crows announce Shinobu's death to the rest of the Demon Slayers.

Zenitsu Agatsuma faces his former senior Kaigaku, who became the new Upper Rank Six after an encounter with Upper Rank One Kokushibo. Angered by Kaigaku's lack of guilt over his betrayal, which led to their master Jigoro committing seppuku, they battle. Kaigaku voices his frustration at being compared to Zenitsu, but is killed when he uses a self-taught Thunder Breathing form. Zenitsu passes out and momentarily enters the afterlife, where Jigoro reaffirms he has always been proud of him; he is then rescued by a disguised Yushiro, who has been using his Blood Demon Art to help the Ubuyashikis map the Infinity Castle. Meanwhile, Nezuko Kamado takes a drug produced by Shinobu and Tamayo to restore her humanity and is placed under the care of Sakonji Urokodaki.

Tanjiro Kamado and Giyu Tomioka fight Upper Rank Three Akaza. Though Giyu unlocks his mark to enhance his power, Akaza continues to overwhelm them. Determining that the demon is able to target people based on their willpower, Tanjiro recalls memories of Inosuke's ability to detect attacks and observing his late father in combat. He enters the Transparent World and Selfless State, giving him heightened perception and masking his emotions, successfully beheading Akaza. However, Akaza's body continues to resist and fight Tanjiro and Giyu while headless, pushing them to the brink.

Their persistence causes Akaza to remember his tragic past; he was a young criminal named Hakuji, who stole to fund his father's medication. After Hakuji was caught stealing numerous times, his father committed suicide to unburden him, leading to a chance encounter with a dojo owner, Keizo. Hakuji served as his sole disciple while caring for his sick daughter, Koyuki. Hakuji and Koyuki eventually became engaged, but she and her father were poisoned by a resentful neighboring dojo that wanted his land while he visited his father's grave. The vengeful Hakuji massacred all of the dojo's members and was turned into a demon during an encounter with Muzan afterwards.

Despite regenerating his head out of sheer will, Akaza realizes his mistakes through his restored memories. Giving a final smile of gratitude to Tanjiro, he fatally injures himself and stops his regeneration, accepting defeat. He reconciles with his loved ones and reunites with Koyuki, who embraces him before accompanying him to Hell. Tanjiro and Giyu pass out from exhaustion as their victory is announced by the Kasugai crows.

Kokushibo and Doma are disappointed by Akaza's death, while the Infinity Castle's owner, Upper Rank Four Nakime, manipulates its layout to confuse the Ubuyashikis. Muzan traps Tamayo in a cocoon of his flesh, remaining confident of his victory over the Demon Slayers.