Summary

In most shōnen anime, the protagonist eventually grows strong enough to rival—or even surpass—the final antagonist. It’s a familiar arc: through training, experience, and sheer determination, the hero unlocks power beyond what seemed possible. However, inDemon Slayer, despite Tanjiro Kamado’s growth, his affinity for Sun Breathing, and his extraordinary resilience, he never reaches a point where he alone can defeat Muzan Kibutsuji. The Demon King’s death was a collective effort, requiringthe combined strength of the Hashira, the Demon Slayer Corps, andLady Tamayo’s lethal poison. This raises a crucial question: was Muzan truly unmatched? The answer is no. There was one man who could—and did—stand against Muzan on equal footing. Yoriichi Tsugikuni, the greatest Demon Slayer in history, remains the only character capable of rivaling the Demon King.

Koyoharu Gotouge’sDemon Slayer: Kimetsu no Yaibafirst debuted as a manga inWeekly Shōnen Jumpin 2016 and concluded in 2020, spanning 23 volumes. The anime adaptation, produced by Ufotable, premiered in April 2019 and quickly became a global sensation. Known for its breathtaking animation, emotionally driven storytelling, and exhilarating action sequences, the series redefined modern shonen anime. Its unprecedented success, culminating inDemon Slayer: Mugen Trainbecoming the highest-grossing anime filmof all time, solidified its place in anime history.

Spoiler Warning:This article contains major spoilers forDemon Slayer: Kimetsu no Yaiba, including key plot points from the final battle against Muzan. If you haven’t finished the series, proceed with caution!

How Powerful Was Muzan Kibutsuji?

The Strength of the Demon King

Muzan Kibutsuji, the progenitor of all demons,was a near-unstoppable force. His regenerative abilities, overwhelming strength, and terrifying speed made him an adversary unlike any other inDemon Slayer. His very presence instilled fear, even among his own subordinates. As the Demon King, Muzan effortlessly annihilated dozens of trained Demon Slayers and stood against multiple Hashira at once. His power was so immense that even marked Hashira—who had enhanced abilities—struggled to keep up with him.

The Four Stages of Muzan’s Weakening

Muzan was only defeated after being strategically weakened.Lady Tamayo’s drug played a crucial role in weakening his abilitiesbefore the final battle. The drug worked in four distinct stages:

Effect

Aging Acceleration

Aged Muzan’s cells by over 9,000 years, drastically reducing his stamina and regeneration.

Prevention of Splitting

Stopped Muzan from breaking his body into thousands of pieces to escape.

Human Conversion

Attempted to forcibly turn Muzan back into a human, further weakening him.

Cellular Destruction

Caused irreversible damage to Muzan’s cells, ensuring he couldn’t heal at his usual rapid pace.

Even with these debuffs, Muzan still managed to push the Demon Slayer Corps to the brink. Without these disadvantages, he would have annihilated the Hashira and the Kamado siblings with ease.

Yoriichi Tsugikuni: The Only True Rival to Muzan

The Strongest Demon Slayer in History

The only person to ever fight Muzan on equal terms was Yoriichi Tsugikuni, the inventor of the Breathing Styles and the strongest Demon Slayer who ever lived. Yoriichi was a once-in-a-millennium prodigy.Born with the Demon Slayer Mark, access to the Transparent World, and an unmatched mastery of the sword, he was leagues beyond every other warrior in the series’ history.

His battle against Muzan was nothing short of legendary. Unlike Tanjiro and the Demon Slayer Corps, who needed numerous advantages to stand a chance, Yoriichi nearly killed Muzan in a one-on-one fight. Recognizing Muzan’s unique physiology, Yoriichi instantly devised a way to strike all seven of his hearts and five brains in a single attack. Muzan, despite his overwhelming power, had no counter for Yoriichi’s precision and technique. He was completely outclassed, unable to fight back, andbarely managed to escape by dispersing himselfinto thousands of pieces.

The encounter left Muzan permanently scarred—both physically and psychologically. The Demon King, who had slaughtered countless Demon Slayers, was so traumatized by Yoriichi that he spent centuries in hiding, ensuring he never faced such a threat again. Even after Yoriichi’s death, the mere sight of his Hanafuda earrings was enough to send Muzan into a panic.

The True Power Ceiling ofDemon Slayer

Even inDemon Slayer’sfinal arc, no character—Tanjiro included—ever approached the power level of Yoriichi or Muzan in their prime. WhileTanjiro inherited Yoriichi’s Sun Breathing, he never reached the same level of mastery. The power ceiling ofDemon Slayerhad already been established centuries before the main story began, with YoriiEven in Demon Slayer’s final arcchi and Muzan being in a class of their own.

Ultimately, while Tanjiro was the series’ hero, he was never Muzan’s true rival. That title belonged solely to Yoriichi Tsugikuni—the only warrior who ever came close to truly ending the Demon King’s reign alone.