Who Is Demon Slayer's Kokushibo? Infinity Castle Part 2's Big Villain Explained

2 weeks ago 12

Published May 9, 2026, 8:30 AM EDT

Branson is a Senior Writer for ScreenRant. Anime has been a major part of his life since he was able to raise his hands in the air for a Spirit Bomb. As a journalist, Branson focuses heavily on listicles and op-eds detailing the industry's greatest shonen series.

Demon Slayer is no stranger to brutal, terrifying villains, and yet, the worst of them all has yet to be properly introduced. Demon Slayer: Infinity Castle showed just how monstrous Akaza truly is, but even he has nothing on the Upper Moon Rank One.

Kokushibo, the strongest Demon in the franchise outside Muzan, will take a prominent role in Demon Slayer: Infinity Castle Part Two. He will most likely be the lead villain in the film, much to the chagrin of the Demon Slayer.

The Demon Slayer franchise has exploded in popularity thanks to a top-tier anime adaptation and some of the best anime films of all time. With Kokushibo finally entering the series, Part Two might be the most exciting addition to the series yet.

This article contains spoilers for the Demon Slayer anime.

Infinity Castle Shined a Light on One of the Series' Most Brutal Villains, But...

Demon Slayer: Infinity Castle was a cut above most anime films. It has great animation, one of the best fights in the entire franchise, and sets the stage for what is looking to be an absolutely thrilling conclusion to one of the best shōnen franchises of the modern era.

Akaza is easily one of the best villains in anime. His martial arts perfectly contradicts the Demon Slayer's sword-based attacks, his ferocity is second to none, and even his sheer presence is enough to make anyone's hair stand up. His brutal victory over Rengoku in Infinity Train gave Tanjiro the motivation he needed to avenge one of the strongest Hashira in Demon Slayer.

Every New & Returning Character in Demon Slayer’s Infinity Castle

Demon Slayer's Infinity Castle movie is easily the most highly anticipated anime film of all time, but which characters are set to play a major role?

While the first film was rightfully centered around Akaza, Doma, the Upper Moon Rank Two, was also introduced. Unlike Kaigaku, the Upper Moon Rank Six that Zenitsu dispatched with impeccable precision, Doma lived, destined to play a large role in the next film.

Out of every Demon, including Muzan Kibutsuji himself, however, there isn't a Demon who will play as big a role in the second film as the Upper Moon Rank One himself, Kokushibo.

... Kokushibo is 10x the Villain Akaza Is

Kokushibo is the most frightening character in Demon Slayer. While he might not be as strong as his master Muzan, his cold demeanor and ruthless aggression set him apart from every other villain in the franchise. Akaza, Doma, and even Gyutaro are all terrifying in their own right, but none of the other Upper Moons can hold a candle to Kokushibo.

Kokushibo is such a threat that he might be able to kill all the other Upper Moons simultaneously. He's the only Demon to use a sword, and that's because before he was a Demon, he was one of the strongest Demon Slayers in history. He's the long-forgotten twin brother of Yoriichi Tsugikuni, the single strongest Demon Slayer of all time.

Before he became Kokushibo, he was known as Michikatsu Tsugikuni. He's arguably the second-strongest Demon Slayer ever, behind his brother. Because his brother was so much stronger than him, however, Michikatsu became incredibly jealous. Muzan offered him a chance to become stronger, and Michikatsu became Kokushibo.

Kokushibo was never even remotely close to Yoriichi, even after becoming a Demon. During a fight, Yoriichi was moments away from beheading his brother, only to die of old age in the middle of the fight. Since then, Kokushibo has had no equal. He is basically untouchable in terms of strength, and Demon Slayer: Infinity Castle Part Two will show exactly why he's held the rank of Upper Moon One for hundreds of years.