This article contains spoilers from Demon Slayer’s manga.
Summary
- Muzan’s near-death encounter with Yoriichi shaped his actions against demon slayers.
- Yoriichi’s fight with Muzan laid the foundation for the victory of the next generation of demon slayers.
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500 years before the events of Demon Slayer, Muzan Kibutsuji escapes a gruesome death at the hands of Yoriichi Tsugikuni, the first Sun Breather and the inventor of all breathing styles. While Yoriichi failed to kill Muzan, the progenitor of all demons developed an intense fear of Yoriichi and Sun Breathing, which shaped the course of history in Demon Slayer.
Muzan Kibutsuji’s near-death encounter influenced his actions and decisions against the demon slayers, particularly Tanjiro Kamado and his family. After all, it was the only time in the history of the series that Muzan, the Demon King, was utterly overpowered by a lone demon slayer.

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Muzan’s Fateful Encounter With Yoriichi
Muzan Avoided Death Multiple Times
Muzan Kibutsuji had several near-death experiences prior to his fateful encounter with Yoriichi Tsugikuni. Before Muzan became a demon, his heart stopped several times in his mother’s womb, and when he was born, he was almost cremated since he was pronounced stillborn. Muzan’s misfortunes did not end there; he was afflicted with a terminal illness that may have killed him at a very young age. Unfortunately, death is perpetually at Muzan’s doorstep throughout his human years.
“The first time I saw him, he looked very weak. There was no ambition, no willpower, no hatred, and no killing intent. Yet that man would decapitate and slash at me.”—Muzan Kibutsuji
After Muzan turned into a demon, he became a force to be reckoned with despite his inability to walk in the sunlight. For years, Muzan’s unmatched power rendered him unstoppable, and no one dared stand against him, not even Michikatsu Tsugikuni, who later became Kokushibo, the Upper One Moon. However, there exists a young man named Yoriichi, the most powerful demon slayer in history, whose purpose in life is to end Muzan and his violent intentions.

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Muzan’s Showdown With Yoriichi
Muzan and Yoriichi first encountered each other in a bamboo forest sometime after Muzan turned Michikatsu into a demon. Back then, Muzan was with Tamayo, who witnessed the showdown unfold in her very eyes. Meanwhile, Yoriichi felt chills down his spine upon seeing Muzan, fearing that a single scratch from the demon would be fatal due to his fearsome speed and long reach. Worse, after looking into the Transparent World, Yoriichi also discovered that Muzan had seven hearts and five brains.
“What is the value of life to you?”—Yoriichi Tsugikuni to Muzan Kibutsuji
However, Muzan did not expect Yoriichi to complete all forms of his Sun Breathing and combine them in a single devastating strike, leaving him with a severed head and a body that refused to regenerate. This led Yoriichi to believe that his Bright Red Nichirin Sword could finally end Muzan. For the first time, the proud Demon King found himself on the brink of death at the hands of a demon slayer.
Muzan’s Desperate Attempt to Escape Death
But before Yoriichi could finish off Muzan, the demon’s entire body broke into hundreds of small pieces, much to Yoriichi’s surprise. Out of all the 1,800 pieces, Yoriichi cut a little more than 1,500 off Muzan’s body fragments, leaving the remainder to reassemble into a lump the size of a human head. It was Muzan’s frantic attempt to flee from Yoriichi, even if it meant leaving Tamayo behind. While Muzan managed to escape death, he couldn’t escape the trauma caused by the encounter with Yoriichi.
For years, Muzan avoided confrontation with Sun Breathers, all while turning humans into demons in search of a special demon capable of walking in the sunlight. In Demon Slayer, Yoriichi may have failed in killing Muzan, but the result of the fight between them paved a path to victory for the next generation of demon slayers. And in the end, Yoriichi’s legacy assured that Muzan could never run nor escape forever.
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