Demon Slayer fans misunderstood the purpose of Muzan's extra organs

With the Demon Slayer anime series nearing its conclusion in the upcoming seasons, several fans have expressed their opinions on facts from the series. When the manga concluded in May 2020, the series revealed even more information about the main antagonist, Kibutsuji Muzan, which has yet to be seen in the anime.

One revelation is Muzan's possession of multiple internal organs compared to normal human physiology, specifically seven hearts and five brains. The fandom has been mocking Muzan for having five brains yet demonstrating stupidity; however, their reasoning may be flawed regarding the purpose of these organs.

Disclaimer: This article contains speculative theory and reflects the author's opinions. It also contains spoilers from the Demon Slayer manga.

---

Fans might be mocking Muzan for the wrong reasons in Demon Slayer

Chapter 187 reveals Muzan having multiple organs in his body (Image via Shueisha)

In chapter 187 of the Demon Slayer manga, titled Innocent Person, mangaka Koyoharu Gotouge reveals Muzan has seven hearts and five brains during his confrontation with Yoriichi Tsugikuni in a flashback. Ever since this revelation, fans have been criticizing Muzan for making some questionable choices for someone with five brains.

The criticism mainly revolves around some drastic decisions Muzan made throughout the series, such as killing the Lower Moon demons, not killing Tanjiro during their previous encounter in Asakusa, leaving the corpses of the Kamado family for Tanjiro to discover after killing them, and not launching a full-scale attack on the Demon Slayer Corps after Gyutaro and Daki were defeated, among others.

While changes in these instances would have significantly impacted the narrative, fans continue to debate how Muzan could have acted differently, given he is supposed to be the smartest character with five brains.

Fans may be partially correct in correlating the facts and events. However, the extra organs might serve a different purpose related to his particular combat style, which many in the fandom have overlooked, and this also makes total sense.

Muzan's extra organs could simply provide the vitality and stability needed for his Blood Demon Art to function efficiently. Muzan's Blood Demon Art, Biokinesis, allows him to fully control and reshape his body, forming elongated flesh whips from his extremities. His ability also enables him to shapeshift, rearrange his internal organs, and even create new ones.

The extra organs likely assist in coordinating this ability. The additional brains Muzan has most likely help coordinate his movements after he creates the overgrown tentacles and whips, enhancing his motor functions. The extra hearts aid in pumping blood into his tissues, boosting his regeneration powers while also providing an energy boost. Furthermore, they help immunize Muzan against dying from being beheaded by a Nichirin weapon.

---

Final thoughts

While the Demon Slayer series does not explicitly clarify the purpose of Muzan's extra organs, the discussed possibility can be considered a viable explanation based on the facts presented by the series.

Muzan's alleged "stupidity" is a key part of the narrative that would have changed the story if he had acted differently. With the upcoming Infinity Castle arc, the full exploration of Muzan's powers will be revealed in the anime series as he is set to face the Demon Slayers in a final battle, with a small glimpse seen during the final moments of the previous arc, the Hashira Training arc.

---