How Did Muzan Find Out That Nezuko Is Immune to Sunlight?

Alongside Tanjiro, her younger brother, Nezuko Kamado, is probably the most important character in the Demon Slayer franchise. On the dreaded night that changed the protagonists’ lives, Nezuko was turned into a demon by Muzan Kibutsuji, and Tanjiro made it his goal to find a way to return Nezuko to her human form. Being special, Nezuko retained a large portion of her initial humanity and never attacked humans, but she also has some other unique abilities as well, and one of them is her resistance to the Sun. This ability was finally revealed in the final episode of the third season of Demon Slayer, and while it seemed that this fact would only bring joy to the protagonists, it turned out that Muzan, the series’ main villain, found out about it and in this article, we are going to tell you how that happened.

Although Nezuko was initially burned by the sun, and it seemed that she would die, a short timespan that Tanjiro forcibly used to finish off Hantengu, she eventually rose, completely healthy and normal, proving that she was able to conquer the Sun. Sadly, Hantengu did not completely disappear before Nezuko stood up, and he simply used the last of his remaining energy to telepathically send a message to Muzan that Nezuko was somehow immune to sunlight, which made Muzan quite ecstatic.

The rest of this article will focus on Nezuko Kamado and her ability to conquer the Sun in the series. Now, we’ll be telling you what happened in the series and how Muzan Kibutsuji, who was nowhere near the Swordsmith Village at the time, found out that Nezuko was immune to sunlight. Nezuko Kamado is a uniquely special character in the Demon Slayer manga, so she deserves a standalone article, although we have to warn you that a lot of spoilers will be present, so be careful how you approach the text.

Muznan found out about Nezuko’s unique ability thanks to Hantengu

As we have said, Nezuko’s ability to conquer the Sun is unique when demons are concerned. Namely, Demons are generally weak to sunlight, and if exposed to it, the sunlight will kill them. Even Muzan is not an exception to this. But, as Muzan hypothesized, the blue spider lily could cure demons of that weakness or, since he could not really find that flower, a demon could be born with a natural resistance to sunlight, but this would be extremely rare.

Muzan waited for around a millennium for such a thing to happen, and had Hantengu not been there, he would never have found out about it. So, what happened?

The events we are about to describe happened during the battle against Hantengu, the Upper-Rank Four, or, to be more precise, during the end of that battle. Namely, as the fight was approaching its end, the sun started to rise. At that moment, Nezuko, in her demon form, was still on the battlefield, and while Tanjiro pleaded with her to leave, regardless of what would happen during his fight with Hantengu, Nezuko decided to remain there and sacrifice herself, if needed, to defeat Hantengu. And that seemingly happened once the sunlight came into contact with her skin.

The sun then burned Nezuko, and she was seemingly dying, as you’d expect from a demon, leaving her brother in tears. Still being forced to do it, Tanjiro then proceeded to kill Hantengu and quickly returned to his seemingly dying sister, but a miracle happened then. Namely, a fully recovered Nezuko stood up and greeted her brother, which shocked him and made him extremely happy because it had happened. No one knew what had happened, but aside from being alive and speaking, Nezuko looked much more human than before.

This prompted Tanjiro to ask her whether she managed to regain her humanity, but when Neuzko simply started repeating his words, he realized that she was still a demon; but that didn’t really matter, as they were all overjoyed with Nezuko being alive more than anything else. So, what actually happened? Nezuko managed to conquer the Sun, which was a major moment in the life of a demon.

She also proved that her human side was still quite potent, which helped her regain a part of her humanity, but she was still not completely human. Lady Tamayo explained the reasons behind this in her letter, but we won’t be going back to that issue in this article. What interests us at this moment is how Muzan found out. Wait, Muzan found out?

Of course, Muzan found out. The guy has been searching for a cure to his weakness for a millennium, and you think he’d let such an important fact slip past him? Well, had it not been for Hantengu, he actually would have, so our dramatic introduction to the issue was actually intended to be ironic.

So, what happened? We know that demons are able to communicate with Muzan telepathically, and that is the key fact you need to know before we tell you what happened.

Namely, as Tanjiro killed Hantengu, the demon was slowly disappearing, but before he fully disappeared and died, Hantengu observed Nezuko’s “resurrection” and saw that the young girl actually managed to conquer the Sun. Being the loyal coward he is, Hantengu uses the little energy he has left to contact Muzan and tell him what happened. Muzan, who was then posing as a young boy, was so excited that he killed his “mother” and the maid of “his” household, thrilled to know that he was closer to his goal.

Muzan then decided to make Nezuko his primary target, believing that consuming Nezuko would give him her resistance. Luckily for her, he failed to capture her, and she would later be turned back into a human, completely crushing Muzan’s chances of becoming resistant to sunlight.