Demon Slayer's The latest installment came in 2025, when the series began its final trilogy with Infinity Castle Part 1 — Akaza's Return. It's been a year since that movie came out and we still haven't received an official update on the next movie's release date. Nonetheless, we're still very excited about this new movie, and for those of us who have read the manga, we're eager to see the series' ultimate transformation: Tanjiro's Demon Lord form.
At the end of Demon Slayer, Tanjiro is transformed into a demon lord by Muzan, and he becomes the most powerful character in the entire world. This transformation was eventually reversed, but for a short time it created a character much stronger than Muzan or Yoriichi. Ufotable's Demon Slayer animation is preparing this format for a 2029 release, when Infinity Castle Part 3 opens in theaters.
In Demon Slayer: Infinity Castle Part 3, Tanjiro's transformation into the Demon Lord will be revealed, making him the strongest.
demon slayer The series has been going strong since 2019, when it received its first TV animation via Ufotable Studio. Since then we've gotten a second, third, and fourth season and three movies. The latest film is Demon Slayer: Infinity Castle Part 1, which was officially released on July 18, 2025, followed by two more films to complete the Demon Slayer trilogy. Two more films are currently planned, known as Infinity Castle Part 2 and Infinity Castle Part 3, and Part 3 will undoubtedly be the one that takes the biggest stakes. In Infinity Castle Part 3, the final battle with Muzan begins. Of course, like any shonen's story, once the battle is over, the Demon Slayers will find a way to take down the villain, even if it means great sacrifice.
Looking at the manga, we saw Muzan's downfall in Episode 200 of Demon Slayer, which was released in the 18th issue of Weekly Shonen Jump on March 30, 2020. But to everyone's shock, that wasn't exactly the end of him. Before Muzan's body completely disintegrates, he decides to transfer his blood and living cells to Tanjiro, the protagonist of the story. This development occurs in Demon Slayer Episode 201 of Shueisha Weekly Shonen Jump Issue 19 on April 6, 2020. Due to Muzan's blood transfer, a demonic transformation begins within Tanjiro, who becomes officially known as Demon King Tanjiro.
In this form, Tanjiro is basically transforming into a new Muzan. This form of Tanjiro would be a greater danger to the world than Muzan, making him the most powerful character of all time. This form is undoubtedly Tanjiro's strongest form, and is also the most powerful transformation throughout the entire story. In this form, Tanjiro develops demon-like characteristics such as slanted eyes and serrated teeth. He is also marked with flame-shaped marks all over his body, as seen in Muzan's final form, Kokushibo.
“My body will soon fall under the sunlight, but… my memories are also eternal and indestructible. I too will pass on my memories to this boy. My breathing and heart are declining, but all my cells are not destroyed. There is still time. I will pour all my blood and strength into him, so that I will not be defeated even by death. Together with Tanjiro Kamado, I will conquer the sun and become the strongest demon king. Thanks to your blood, you are unique, just like Nezuko Kamado. You will not die. Do I believe that with you all my dreams will come true.” — Muzan to Tanjiro in Demon Slayer Episode 201
As far as manga is concerned, Demon Slayer Chapter 203, released on April 27, 2020 in Shueisha Weekly Shonen Jump Double Issue #21-22, saw this change reversed through the cumulative efforts of Nezuko, Kanao, and Shinobu.
Using Scarlet Eyes, the final form of Flower Breath, Kanao is able to inject Tanjiro with the anti-demon antidote given to her by Shinobu, while Nezuko captures him and attempts to communicate with the remaining humanity he left behind before his full transformation. Tanjiro also rejects Muzan, regains his mind, and awakens as a human once again. Sure, Tanjiro's form was insanely overpowering, but he was left with a big debuff after resisting it. Tanjiro is permanently blind in one eye, and his regenerated arm resembles that of an old man and cannot be moved properly.
All the powers and abilities of Demon King Tanjiro
Tanjiro's abilities are not fully known, as he is never at his full potential due to the speed with which he is transformed into Demon King Tanjiro and rescued. What we saw wasn't even a complete change. However, looking at Muzan's performance, you can see what kind of beast Tanjiro must have been even in his base form. In The Sunrise arc, the Demon Slayers fought Muzan, and it was clear that he could not kill them with a sword slash. This depends on his regeneration as he is said to be the best of all demons. What's even more impressive is that Muzan's regeneration itself was momentarily nerfed. Muzan was also able to sprout tentacle-like organs from his body and use them in battle. As Tanjiro transforms, the same tentacles seem to sprout out.
From Muzan's own statements, we know that Tanjiro would have been much stronger than him, and broadly speaking, there are two abilities that Muzan does not have. First of all, Tanjiro is probably a demon immune to the sun, just like Nezuko. The sun is the devil's greatest weakness, and these two defeated it. Muzan's ultimate goal was always to gain solar resistance, but he failed where Tanjiro succeeded. The only way for Muzan to be defeated was to stop him until the sun rose, making the Demon Lord invincible with sun resistance.
Another powerful ability that Tanjiro has that Muzan does not have is solar breathing. Breath of the Sun is the only weakness the Demon Lord can have, and this is how Yoriichi defeated Muzan. However, due to Tanjiro's resistance to the sun and his mastery of swordsmanship, even that would have been useless to him.
Demon King Tanjiro surpasses Muzan and Yoriichi and undergoes the series' strongest transformation.
Demon King Tanjiro is definitely the strongest character in the Demon Slayer story. Muzan himself stated that he intended to make Tanjiro the most powerful Demon King of all time, which is more than reflected in his strength and abilities that defy the power of a typical Demon King. Moreover, in this form, Tanjiro undoubtedly surpasses even Yoriichi, the founder of solar breathing and all breathing methods.
Yoriichi was a talented swordsman like no other, and he quickly struck down Muzan at full strength and almost killed him. However, if Yoriichi and Demon King Tanjiro face off, such a victory will not be possible. Yoriichi can stand up to Demon Lord Tanjiro, but he has no way of dealing a fatal blow to him. Sun Breathing is not effective due to Tanjiro's solar resistance and does not work if stopped until sunrise. In the end, Tanjiro reached the top and defeated Yoriichi.
Demon Slayer: Infinity Castle Part 1 will be available to watch on Crunchyroll starting July 28, 2026.
