Who is Kokushibo in Demon Slayer Infinity Castle? The Upper Moon 1 and Muzan's right-hand man explained

Kokushibo has long been teased in the Demon Slayer universe, and now, thanks to the recent Demon Slayer Infinity Castle movie, it seems like we are closer than ever to seeing the demon finally take the spotlight.

As one of the best anime around, Demon Slayer is packed with intriguing characters. However, over multiple seasons and flicks of Tanjiro and the Demon Corps fighting through the Twelve Kizuki, Kokushibo (aka the Upper Moon 1) is one of the most anticipated foes, grabbing all of our attention when he first appeared during the Swordsmith Village Arc with his glowing six eyes and curious Demon Slayer Mark across his face. Luckily, he does appear in Demon Slayer Infinity Castle, and is also hinted to be a big part in the next upcoming movie as well.

So, to catch you up on some Demon Slayer lore as well as break down some manga spoilers, we've created a handy guide on one of the most intriguing villains in the anime period. But be warned, heavy manga spoilers are ahead. So proceed with caution. If you are after a spoiler-free refresher on the franchise, you can head to our Demon Slayer in order guide. But for now, let's dive into all the ins and outs about Kokushibo.

Who is Kokushibo?

When we meet him, Kokushibo is a demon who is part of the Twelve Kizuki. He is also the highest-ranked member of Muzan's group, holding the position of Upper Rank One of the Upper Moons. He also possesses the technique of Moon Breathing, which, combined with his Demon Blood Art, lets him use a flurry of crescent moon-shaped blades during attacks. Talk about intimidating, right?

However, cool abilities aside, among all the demons, Kokushibo has long stood out to fans, given his uncanny resemblance to Yoriichi Tsugikuni and Tanjiro himself. While we haven't seen a lot of Kokushibo yet (having only received glimpses of him during the Swordsmith Village Arc and the most recent movie, Demon Slayer: Infinity Castle), the demon has a very intriguing backstory and connection with the Demon Slayer Corps. Over 500 years before the events of the main anime, during the Sengoku Era, Kokushibo was a human called Michikatsu Tsugikuni, and the twin brother of Yoriichi (aka the strongest Demon Slayer around).

Kokushibo and Yoriichi may have been twins, but they had a very different upbringing due to Yoriichi's birthmark, causing him to have an isolated and rough childhood after being sent to a temple. Kokushibo often pitted his brother, who wished to be a samurai like him. However, this pity was short-lived once Yoriichi actually got hold of the sword and proved to be a genius, surpassing his brother completely. To make matters worse, Yoriichi hated combat and stopped dreaming of a samurai future - wasting his potential in Kokushibo's eyes.

Kokushibo started to pursue mastering the blade with extreme intensity. His jealousy for his brother grew, and so did his resentment. He didn't see his brother again for about ten years until he was saved by Yoriichi after being attacked by a demon one night. Seeing his brother again, who had become even more impressive, renewed his jealousy once again, and Kokushibo chose to abandon his wife and children in order to become a Demon Slayer and train with Yoriichi.

He eventually developed his own Demon Slayer Mark and Breathing Technique (Moon Breathing), but he still wasn't as powerful as Yoriichi. All these negative feelings made him a prime manipulation target for Muzan, and Kokushibo agreed to become a demon. Being a demon, he built up his strength and finally faced his brother again after 60 years. Seeing his brother old, disgusted him, as well as enraged him, since Demon Slayer marks normally mean young deaths, yet his brother had lived a full life.

Despite Yoriichi being old, he was still powerful too, almost killing his brother. However, Kokushibo did not kill the old Demon Slayer or die by his hand; rather, he watched in horror as his undefeated brother died from old age rather than by his sword. Kokushibo now lives with the fact that he'll never get that fair fight with his brother or truly surpass him. Still, he is obsessed with not being weak and building strength…pretty sad if you ask us.

Is Kokushibo related to Tanjiro?

No, despite him and his twin brother sporting similar hair and features to our main Demon Slaying protagonist, Kokushibo isn't technically related to Tanjiro. However, he is a long-lost ancestor of another Demon Slayer.

Remember how I mentioned that Kokushibo left his wife and kids to follow his brother after a demon attack? Well, it turns out that his bloodline continued even if his family name died out. Muichiro Tokito (aka the Mist Hashira) comes from Kokushibo's abandoned family, making him the ancestor of the talented swordsman.

The connection that Kokushibo and Tanjiro do have is an indirect one: they both have ties to Yoriichi. Tanjiro's family was taught Yoriichi's Sun Breathing technique, which is what all other breathing techniques are derived from, including Kokushibo's Moon Breathing technique. Unfortunately ( in the manga anyway), the two never meet or fight, so don't expect any drama there, folks. Instead, we can all look forward to Kokushibo facing off against the ancestor of the child he left behind, Muichiro.

Will Kokushibo be in Demon Slayer Infinity Castle 2?

While it hasn't been fully confirmed yet, we are betting that Kokushibo is heavily in Demon Slayer Infinity Castle 2. The events of the first movie ended just before chapter 158 of the manga, and in chapter 164, we'll see Kokushibo and Muichiro meet before their fight in chapter 165.

So yeah, it's basically a given that Kokushibo will be a big player in the next movie since that is the next big event in the Infinity Castle Arc manga. We'll keep you posted as more details head our way regarding how much of the Upper Rank One demon we will see, but at least we can rest easy knowing that he's likely going to be the next big bad focal point of the franchise in Muzan Kibutsuji's absence.

For more details, check out our Demon Slayer: Infinity Castle review, or head over to in in-depth guide on the Demon Slayer: Infinity Castle ending explained.