Demon Slayer: Infinity Castle Movie Will Reveal a Mysterious Demon Who Can Use a Demon Slayer Mark

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The following contains spoilers from the Demon Slayer: Kimetsu no Yaiba manga and anime.

For more than a thousand years, Warriors Against Demons have been engaged in an unending battle against demons. In spite of their physical frailty when confronting supernaturally powerful beings, these courageous fighters have repeatedly risked their lives through the ages.

However, during the Sengoku period, everything shifted when Yoriichi bestowed the Demon Slayer Mark upon someone. This enigmatic emblem granted a swordsman the opportunity to battle against some of the strongest demons known to exist. Interestingly, while the Demon Slayer Mark is generally seen as a great boon for a swordsman, the Infinity Castle trilogy hints at a demon who can utilize this mark, even surpassing the abilities of many Demon Slayers.

The Demon Who Can Use the Demon Slayer Mark

Kokushibo is the Only Demon With the Mark

In the past, the enigmatic Demon Slayer Mark was a power that only a select number of sword-wielders could unlock. During the Taisho Period, Tanjiro was the first to uncover this hidden potential, followed by Muichiro Tokito and Mitsuri Kanroji. But it was during the Sengoku Era when this mysterious marking made its debut, born alongside the legendary swordsman Yoriichi Tsugikuni.

Let me help you rephrase the given line in a more natural and easy-to-understand manner:

If I don’t stop your bleeding, humans are so fragile that they can easily die from blood loss. However, if death is already your destiny—either because you bleed to death or because his lordship doesn’t approve of you and you meet your end as a result—then in such a case, you were no better than anyone else. Isn’t that true? ~ Kokushibo to Muichiro

This version retains the original meaning but aims to make it more accessible for readers by using clearer language, simplifying sentence structures, and avoiding archaic expressions.

Since the inception of the Demon Slayer Corps, the Demon Slayer Mark has been a distinctive power exclusive to its members. However, there’s an exception – Upper Moon One, Kokushibo, bears the mark as well. Remarkably, he is proficient in utilizing it and seems to have a deep understanding of its uses.

During the Infinity Castle storyline, Kokushibo frequently entered a state where he could see right through Sanemi, Genya, Muichiro, and Gyomei, as if their bodies were completely transparent. This unique power, known as the Transparent World, is a special ability that only those bearing the Demon Slayer Mark can access.

With this distinctive method, Kokushibo unraveled that Genya feeds on demons and Muichiro is his descendant. Moreover, as the battle intensified, he also deduced each Demon Slayer’s key strengths and vulnerabilities to leverage them in combat. However, the enigma surrounding the mystical marking on a demon has likely left fans scratching their heads for quite some time. This question surely must have been perplexing!

Kokushibo’s Origins: How Can the Upper Moon One Use the Mark?

Kokushibo Was Once a Swordsman Back in the Sengoku Era

  • Manga Debut: Chapter 99
  • Anime Debut: Episode 45

One of the oldest demons still living is Upper Rank One. He initially served under Muzan during the Sengoku period. Prior to his demonic transformation, he was a highly skilled swordsman associated with the Demon Slayer Organization. Remarkably, he lived during the Golden Age of Demon Slayers. Upon awakening the mark, however, he discovered that any swordsman who exhibits this mark does not survive past the age of 25.

Eager to defy mortality and enhance his strength, the demon slayer agreed to Muzan’s proposition, transforming himself into a demon. His wish came true as he was freed from premature death fears and granted ample time to perfect his swordplay, surpassing that of any individual who has ever lived.

Despite transforming into Kokushibo, the Demon Slayer Mark still persisted on him. This made Kokushibo, as Upper Moon One, the sole demon carrying this mark. Over time, Kokushibo became more proficient than anyone else in understanding and utilizing the mark’s abilities during battles. By the outbreak of the full-scale war between the Demon Slayer Corps and Muzan’s forces, Kokushibo had mastered the skill to freely enter the Transparent World.

In the Infinity Castle, as the Demon Slayer Group encounters the Upper Rank One, they’ll discover not just a demon, but an extraordinary swordsman who surpasses them in most areas, making Kokushibo. The way he wields his mark will only complicate matters for the Demon Slayers. To make things even more challenging, the Upper Moon possesses Blood Demon Art, which makes it incredibly tough to defeat him.

The initial part of the Demon Slayer: Infinity Castle trilogy will debut in the U.S. on September 12, 2025.

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2025-07-25 17:17