This article covers the events of Infinity Castle and Sunrise Countdown Arcs from the manga.
Over the last few years, Demon Slayer has cemented itself as one of the most renowned anime and manga series globally. Originally created by Koyoharu Gotouge, Demon Slayer’s simple but exciting story has reeled in millions of fans, and the series has also delivered theatrical box office hits, becoming one of the most financially successful anime series of all time. This was especially the case for its most recent release, Demon Slayer: Infinity Castle Part 1 — Akaza’s Return. Akaza’s Return marks the official beginning of the trilogy that is set to wrap up the story.
With new releases anticipated in 2027, we’re about to see even more fearsome enemies and higher-stakes fights unfold. Demon Slayer: Infinity Castle Part 2, projected to be released in 2027, is about to showcase the defeat of Doma and Kokoshibo, with the third and final movie finally taking us to the final boss — the King of Demons himself, Muzan. Being the strongest Demon, Muzan is set to undertake the most powerful transformation seen in Demon Slayer. His final form has proven to be his physically strongest and most ferocious one, despite the regeneration nerf he has. The Hashira and other Demon Slayers are soon to be in for their toughest fight yet against the strongest villain of all of Demon Slayer.
Muzan Is Officially Set To Unveil His Strongest Transformation In Demon Slayer’s Next Movie Release
In Demon Slayer Season 4 Episode 8, the franchise finally set up its final arcs. In the finale of the season, we saw Muzan get blown up to smithereens via a trick plan concocted by Kagaya Ubuyashiki. While the explosion itself wasn’t enough to kill Muzan, he was weakened then and there, which gave Tamayo the chance to grapple with him and inject him with the Anti-Muzan drug. It is because of this plan that Muzan is and will continue to be absent for the vast majority of the Infinity Castle story. As things stand, Muzan is trying to recover and gather his strength back to fight and survive the battle against the Slayers.
In Infinity Castle Part 1, which was released in Japan on July 18, 2025, Akaza stood as the main villain. In the second movie, Infinity Castle Part 2, which is anticipated for a 2027 release, we will instead see Muzan’s two strongest underlings fall, those being the Upper Rank 1, Kokushibo, and Upper Rank 2, Doma. It’s only in the final movie, which is tentatively referred to as Demon Slayer: Infinity Castle Part 3, that we will see Muzan rise again.
“That’s enough. Not a single one of them has been of use to me. But I will eliminate the Slayers tonight. From here on, I will massacre them all.” — Muzan Showcasing his New form in Demon Slayer chapter 180
In the final release, Muzan will be seen breaking out of his cocoon, where he had been gathering strength, to go all out in battle. In the manga, Demon Slayer Chapter 180, published in Weekly Shonen Jump Issue 48 on October 28, 2019, shows Muzan breaking free, and we also get to see him take on a completely different form from what we’re used to. Instead of his black hair, he sports long, flowy white hair with marks all over his body. Additionally, red marks cover his body, with new mouths sprouting. With the Infinity Castle crumbled and destroyed, Muzan shows his final transformation, which he takes on to fight in a last dance to defeat the Hashira and Demon Slayers before the sun rises.
Gotouge did a phenomenal job in this battle, showcasing Muzan’s most aggressive fighting style, as he unleashed a flurry of abilities that fans had never seen before. Notably, upon his awakening, we got to see him with new sprouted tentacles to fight the Slayers. In his final transformation, Muzan made use of 9 back whips, each 4 meters long, as well as 8 thigh whips of 9 meters in length. These tentacles proved to be extremely fast and deadly weapons, capable of slicing and smacking the Demon Slayers into smithereens upon contact. With the mouths covering them, Muzan could even suck in any Slayer he wanted to destroy.
“Look at it this way. Being killed by me is the same as encountering a great calamity. You don’t need to think too hard about it. Rains, winds, volcanoes, earthquakes. You can’t get revenge on a natural disaster, no matter how many lives it takes away. You can’t bring dead humans back to life. Why not just stop fussing over the issue all the time, and live quietly to earn your daily wages.” — Muzan to Tanjiro in Demon Slayer chapter 181
As far as the manga goes, every capable Demon Slayer had to pick up their weapon and take on the battle to fight this form of Muzan. To portray the level of threat that Muzan posed, Gotouge had all the remaining Hashira, notably Gyomei, Sanemi, Giyu, Mitsuri, and Obanai, take up their swords to battle him, as they were joined by our main character Tanjiro, as well as Zenitsu, Inosuke, and Kanao, in addition to other minor Demon Slayers that tried their best to support them with what little abilities they had. Undoubtedly, Muzan’s strength was shown to be terrifying, and it was stated that his power is far above any of the Upper Ranks. Even with all these Slayers fighting him at once, he did not crumble for a second. Any attack that hit him, he was able to regenerate from immediately. It’ll be interesting to see how Infinity Castle movies bring all these abilities of Muzan to life later down the line.
By the end of the battle, Muzan’s final form is, undoubtedly, set up to be the deadliest one out there. Not only did he kill an array of random Demon Slayers, but he also took down three of the Hashira, those being Mitsuri, Obanai, and Gyomei. They succumbed after the battle to their injuries, and that is despite everyone making use of their strongest abilities. Tanjiro even tapped into his final form of Sun Breathing, and the Hashira unlocked the Transparent World, the Bright Red Nichirin, and their Demon Slayer Marks. Yet all of their efforts weren’t enough, and at the end of it all, only the Sun could deal the final blow to Muzan, his ultimate weakness that he never overcame.
Muzan’s White Form Is His Strongest Transformation Despite Regeneration Nerf
It must be said that, battle-wise, Muzan’s white form is the strongest that we’ve seen. Technically, this form is still nerfed, and Muzan, without the efforts of Shinobu and Tamayo, would’ve been far stronger and deadlier in the final arc. Because the former injected Muzan with the anti-Muzan drug that caused him to age and slow down his regeneration, the day was saved. Muzan’s regeneration was far from its peak in the final arc, and it was only made worse when the Demon Slayers unlocked their Bright Red Nichirin Blades and Tanjiro used his Sun Breathing.
At the same time, there were also the unhealed scars from Yoriichi that kept him from fighting at his best. Had Muzan had his full-scale regeneration as well as his white form, he would have simply been unbeatable. Thankfully, we have never seen this form, and because of Muzan’s death in Demon Slayer chapter 201, we will never see this true strongest villain form in action.
Only Tanjiro’s Demon King Form Surpasses Muzan’s Final Form
When speaking about actual villains that the Hashira and Demon Slayers fought, Muzan is the true final enemy, and his white form is the strongest among all antagonists. However, for a brief moment, we almost saw the birth of an even stronger villain with a greater transformation — Demon King Tanjiro.
In Demon Slayer chapter 201, after Muzan’s disintegration was triggered by the sunlight, he hadn’t yet given up and infected Tanjiro with his cells in hopes of making him the new Demon King. Shockingly, Tanjiro’s transformation began. According to Muzan himself, Tanjiro held the potential to surpass his strength as a Demon King with Sun Immunity and the power of mastered Sun Breathing. Luckily for the Demon Slayers, this transformation never went through.
Tanjiro’s Demon King Transformation was interrupted through the combined efforts of Kanao and Nezuko. Nezuko’s words brought Tanjiro back, while Kanao injected him with the anti-demon drug by using her Vermilion Eye. With their help, he was able to regain his humanity, and the birth of an even stronger Demon King than Muzan was fully thwarted.