Demon Slayer: The legendary rival who nearly defeated Muzan

In the world of Demon Slayer: Kimetsu no Yaiba, Muzan Kibutsuji is the ultimate terror a nearly immortal demon who commands overwhelming power, strength, and regenerative abilities. Yet, despite his terrifying might, there is one character whose strength matches his own: Yoriichi Tsugikuni. As Tanjiro Kamado embarks on his journey to defeat Muzan, it’s revealed that no one, not even Tanjiro or the Hashira, could stand against Muzan alone except for the legendary Yoriichi.
Muzan Kibutsuji is the progenitor of all demons, a being who has lived for centuries and become nearly invincible through his monstrous strength and regenerative powers. His ability to heal from almost any injury makes him a nearly indestructible force, and his power allows him to obliterate even the strongest Demon Slayers and Hashira without breaking a sweat. When Muzan faces multiple Hashira at once, his overwhelming dominance seems unbeatable. However, his eventual defeat wasn't simply due to a direct confrontation but a strategic weakening process, including Lady Tamayo’s drug that aged Muzan and crippled his regenerative abilities. Even so, Muzan relentlessly pushed the Demon Slayer Corps to their limits, demonstrating just how terrifying his power truly is.
Despite Muzan’s unmatched power, there was one person who could rival him a name that still sends ripples through the demon world: Yoriichi Tsugikuni. Yoriichi was not only the most powerful Demon Slayer to ever exist, but he was also the creator of the Breathing Styles, the techniques that would define the future of the Demon Slayer Corps.
When Yoriichi faced Muzan in battle, he came dangerously close to ending the demon king’s reign. Armed with his unrivaled swordsmanship and his deep understanding of Muzan’s physiology, Yoriichi was able to strike all seven of Muzan’s hearts and five brains in one precise, devastating attack. Muzan, despite his godlike abilities, was outmatched by Yoriichi’s flawless technique. The battle left Muzan both physically scarred and psychologically broken. For centuries after, Muzan could not shake the fear of facing such a powerful foe again. The mere sight of Yoriichi’s Hanafuda earrings was enough to send him into a panic, a haunting reminder of the one who almost defeated him.
Though Tanjiro and the Hashira are formidable in their own right, none of them can ever hope to reach the level of power held by Yoriichi and Muzan in their primes. Even as Tanjiro inherits Yoriichi’s Sun Breathing and grows stronger through his journey, he never quite reaches the mastery that Yoriichi possessed. The true power ceiling of Demon Slayer was set long before Tanjiro's story began, with Yoriichi and Muzan far beyond any modern-day warrior.
Tanjiro’s final battle against Muzan is only made possible through the combined strength of the entire Demon Slayer Corps and the tactical advantage provided by Lady Tamayo’s drug. This illustrates just how far Tanjiro still has to grow in comparison to Yoriichi’s legendary abilities.
In the end, while Tanjiro is the hero of Demon Slayer, it’s clear that he is not the one capable of directly challenging Muzan. That honor belongs to Yoriichi Tsugikuni, the only warrior who ever truly stood as an equal to the Demon King. Yoriichi’s legacy as the ultimate rival to Muzan endures long after his death, casting a shadow that no one in the Demon Slayer Corps can escape. His power shaped the very foundation of the Corps, and his influence echoes through every battle fought by Tanjiro and his companions. Yoriichi’s unmatched strength remains a symbol of the true pinnacle of power in the Demon Slayer world.