Demon Slayer: Is Kokushibo related to Yoriichi Tsugikuni? Explained

Demon Slayer and the characters of Kokushibo and Yoriichi (Image via Ufotable).
Demon Slayer and the characters of Kokushibo and Yoriichi (Image via Ufotable).

Demon Slayer is a series that has become known worldwide because of the anime adaptation by Ufotable, and this has created a lot of mysteries for anime-only viewers. The anime is still in the middle of the story even though the manga has ended, which is why characters such as Kokushibo, the first Upper Moon demon, and Yoriichi Tsugikuni are still mysteries for the audience.

In that regard, many anime-only viewers have realized that these two characters have a lot of physical similarities and have begun to wonder if they are related in some shape or form. Here is everything that needs to be known about Kokushibo and Yoriichi in the Demon Slayer series.

Disclaimer: This article contains spoilers for the Demon Slayer series.


Exploring the relationship between Kokushibo and Yoriichi in Demon Slayer

Yoriichi and Kokushibo were twin brothers born many centuries ago when the war between Muzan and the Demon Slayer Corps was just beginning. Both men had a profound sibling relationship and cared deeply for each other, going on to become powerful Demon Slayers in the process.

However, Kokushibo held a lot of resentment and envy towards Yoriichi because the latter had become the greatest warrior until that point, even going as far as making Muzan sweat in fear. No matter what Kokushibo could do, Yoriichi was always better than him, which pushed the former to become a demon and pursue greater strength.

Many decades later, Kokushibo found Yoriichi, now an old man and still stronger than him. Yoriichi died while standing, much to his brother's surprise, with the latter finally realizing that he was always loved by the former. Kokushibo would dedicate the following centuries solely to Muzan, acting as an empty shell without goals or dreams and feeling defeat as his strength was all he had left.


The tragedy of the Tsugikuni brothers

Demon Slayer author Koyoharu Gotouge constantly explored the concept of siblings in her story. Whether it was the Kamado siblings, the Rengokus, the Shinazugawas, and so on, relationships between siblings are a major plot point and theme in the story. In that regard, the Tsugikuni brothers might be her most complex and interesting sibling relationship.

Kokushibo never outgrew his envy and resentment of Yoriichi, which only led him to live a shallow and empty life. Yoriichi understood that strength was the end of the road but only part of the road, which is something that his brother couldn't see. That is why when Kokushibo dies at the hands of the Hashira at the end of the manga, he only looks back with regret and sorrow.

His final demon form is an obvious reflection of the monster he had become - a far cry from the majestic samurai he had been in his human years, showing how rotten and corrupted he had become for the shallow pursuit of strength. However, even in his final moments, he held a degree of love and admiration for his long-gone brother.


Demon Slayer has a lot of interesting characters, but the relationship between Kokushibo and Yoriichi might be one of the most fascinating in the entire franchise. It shows a lot of different layers, making them two of the most compelling characters in the series. Hopefully, their big moment in the anime lives up to the hype.

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