The Demon Slayer Mark is an awakening that enhances the demon slayer’s fighting capabilities.
It enables a Hashira to fight against upper-rank demons on equal footing and, in some cases, overwhelm them.
What would happen if a demon had the demon slayer mark? It would definitely be strong enough to be an upper-rank demon.
Now, what if an upper rank had the Demon Slayer Mark? That is exactly the case with Upper-Rank One, Kokushibo.
So, who is Kokushibo? What is his deal? Let’s find it out in this article.
This article contains spoilers for those not caught up with the manga. Read at your own discretion.
Who is Kokushibo?
Kokushibo is a demon affiliated with Twelve Kizuki and holds the highest position of Upper-Rank One.
Making him the second-strongest demon after Muzan, King of Demons. He became a demon nearly 500 years ago, during the Sengoku Era.
The Sengoku Era is revered as the “Golden Age of Demon Slayers,” as during this era, the breathing style was invented by Yoriichi Tsugikuni, the strongest demon slayer.
To know who is Kokushibo and how he ended up as a demon we need to learn who was Kokushibo as a human.
Kokushibo as a Human:
In his human life, he was a hard-working and ambitious demon slayer who wanted to become the strongest swordsman. This hard work and ambition made him the second-strongest swordsman after his younger brother Yoriichi.
Formerly known as Michikatsu Tsugikuni, he was the elder brother of Yoriichi and was jealous of his brother’s growth, strength, and achievements.
Unlike Yoriichi, Michikatsu was not born with a demon slayer mark and awakened it later in his life.
He even unlocked the mark’s skill, Transparent World, and was very proficient with it.
How Did He Become a Demon?
Michikatsu wished to become an ideal samurai. In this quest, he became obsessed with strength, which was further clouded by his jealousy of his brother.
In order to pursue strength, he accepted Muzan’s blood and became a demon.
His demonization, drastically changed his physical appearance, as he acquired two additional sets of eyes.
As a demon, he lived nearly 500 years and became one of the Twelve Kizuki. He held this against numerous challengers and defeated all of them.
Out of all the demons who challenged him, he only let Akaza live. Everyone else who had challenged him was absorbed, using one of his unique skills.
It is believed that is also how Kokushibo consumed humans.
After becoming a demon, he used his blood demon art to augment his moon-breathing techniques, creating Crescent Moon Blades.
This made his attack much more powerful than when used without Blood Demon Art.
Though it is unclear how many breathing technique forms he developed as a human and as a demon separately, each form was supplemented with his Blood Demon Art.
After becoming a demon, he kept using his Nichirin Blade and modified it with his own demonic blood and flesh.
This made the sword more durable and sharper.
How Kokushibo Got His Demon Slayer Mark:
Michikatsu awakened his Demon Slayer Mark during his training under Yuriichi.
The mark drastically increased his speed and strength. He even gained the ability to see a transparent world.
The transparent world technique allows users to perceive the opponent’s blood flow and muscle movement with great precision. Enabling them to predict and dodge them.
The Mark also came with a curse as the user of the Mark will die at the age of 25.
After Michikatsu became immortal as a demon, he was no longer bound by the curse.
After becoming a demon, he was even able to constantly see into Transparent World.
He was so proficient with the technique that he was able to deduce that Mist Hashira, Muichiro Tokito was his descendent, and Genya had consumed demons to gain strength.
The demon even discerned Gyomei, Sanemi, and Muichiro’s strengths. He discerned all of this with just a glance!
Kokushibo was also highly proficient with flesh manipulation, as evidenced by his ability to merge his weapon with his flesh, making the sword very sharp.
After being decapitated, he greatly morphed his body to adopt a beastly and grotesque appearance. He grew appendages, thin tubes, sharp mandibles, and horns.