Kokushibo: An Ultimate Guide to the 2nd Strongest Demon in Demon Slayer

Demon Slayer is a hugely popular anime with millions of fans all around the world. The main reasons why this anime is so beloved are the impressive storyline and breathtaking visuals. However, the characters and their personal stories also resonate with viewers in a special way.

From Tanjiro Kamado to Muzan Kibutsuji, all the characters have their own struggles and personalities. One of the more enigmatic and captivating characters has to be Kokushibo, who has a dark past that has fans of the series intrigued.

So, just who is this character and why is he important? Let’s find out!

Note: this article contains spoilers about the story that only manga readers know about for now. Kokushibo’s story has not yet made it into the anime. Read at your own risk!

Who is Kokushibo?

Who is Kokushibo?

Kokushibo is actually not the character’s real name, which is Tsugikuni Michikatsu. Kokushibo means black death, a name befitting of the character that Michikatsu became later in his life due to jealousy and an inferiority complex.

He was born as a human and trained to become a member of the Demon Slayer Corps. He was successful and even earned himself a reputation as one of the most powerful swordsmen of his time.

He was also one of the very first Breath users ever and was respected despite feeling inferior to his brother. It was his feelings towards his brother, as well as his fear of death and failure, that drove Michikatsu to take the dark path that led him to become a demon.

Kokushibo as a Human

Born as Tsugikuni Michikatsu in the Sengoku Period, Kokushibo started out as a normal human. He was born as one of a pair of twins, and his brother’s name was Yoriicchi. However, back then, twins were seen as a bad omen, and when their dad noticed a strange birthmark on Yoriichi, he stated he would kill his own child.

The boys’ mother was outraged at what her husband said and arranged that Yoriichi would be sent to a temple instead. She vowed that her boy would become a priest when he turned 10. As such, Yoriichi and Michikatsu had different upbringings, with Yoriichi being confined to a small room separate from the rest of the house. He was kept away from Michikatsu.

Jealous Brother

However, Michikatsu snuck around behind their father’s back and visited Yoriichi, for whom he felt bad. He cared for his brother and gave him a flute he made himself as a special gift.

One day, when Michikatsu was practicing sword swings (he was seven at the time), Yoriichi spoke for the first time in his life. He was previously assumed to be deaf. Yoriichi stated that he wanted to become a samurai like his brother, but this was dismissed because he would be sent to a temple as soon as he turned 10.

However, one of the boys’ father’s men offered to give Yoriichi a bit of instruction and the youngster was able to land four blows on the man. Michikatsu was amazed because he could never land a blow on the instructor. He then begged his brother to teach him in secret, but Yoriichi displayed a distaste for combat. After that, Yoriichi stated that he no longer wished to become a samurai, which was something Michikatsu didn’t understand.

Yoriichi did mention that before taking a stance, he would breathe deeply, and examine his bone alignment, blood flow, and muscle contraction. This was a very early form of the Breath of the Sun style that he would later use.

Dark Fear in His Heart

While Michikatsu continued to study the sword, he would become quite skilled but remained envious of his brother. To him, Yoriichi was wasting his natural talents. He was also scared that after Yoriichi’s talent was noticed, the family would send him to the temple instead of his brother.

Yoriichi left the home the night after their mother died, however, and planned to go to the temple before he would be made the family’s successor.

Michikatsu read his mother’s diary after she died, and learned that Yoriichi knew about her illness and when she would die. This led to deep resentment in his heart.

Ten years later, Michikatsu was a gifted samurai and the father of two children. Sadly, we don’t know the names of his wife or children.

A Demon Attack

A demon attacked his camp, but fortunately, Yoriichi was able to rescue Michikatsu and his family. Rather than feeling grateful for the help, Michikatsu’s jealousy grew even deeper.

This led to Michikatsu abandoning his family and becoming a Demon Slayer. He trained under Yoriichi and developed a Breath Style that was derived from his brother’s Breath of the Sun Style. He called his style the Breath of the Moon.

However, this did not satisfy him and his jealousy intensified, along with his feelings of inferiority. He also feared the fate that awaited him as someone who awakened his Demon Slayer Marks.

This is what led to Michikatsu’s decision to become a demon…

Kokushibo as a Demon

Kokushibo as a Demon

Muzan saw Michikatsu’s potential as well as the darkness lurking in his heart. He was able to persuade the Demon Slayer to become a demon. That way, he would not die at the age of 25, as was the fate that he could not escape (or so he believed), as well as surpass his brother.

When he became a demon, Michikatsu’s appearance changed drastically, and he became Kokushibo.

He gained two extra pairs of eyes and became a lot more powerful than he was. Kokushibo gained the rank of Upper One of the Twelve Kizuki—a title he was able to keep for a long time.

Increased Power

Many challengers attempted to kill Kokushibo for his rank, but they all failed. The only one to challenge him and live was Akaza, who was spared because of the challenge he offered Kokushibo.

As a demon, Kokushibo was able to enhance his Breathing Style, being the only demon to use breathing techniques in battle. His Moon Breathing became a very powerful attack-Crescent Moon Blades.

Although he became the very thing he once killed, Kokushibo refused to give up his Nichirin Blade. Instead, he modified it with his flesh and blood to create the Flesh Katana, a very powerful and durable weapon.

Facing His Brother

Sixty years after he became Kokushibo, he faced his brother in battle. Yoriichi expressed his regret that he had to now slay his own brother and outclassed Kokushibi utterly. In fact, Yoriichi was so much stronger that he slit his brother’s throat.

However, before he could completely cut Kokushibo’s head off and kill him for good, the demon was saved by luck. Yoriichi died on the spot of old age (he had lived to be 85 years old, and didn’t die at 25 as was expected).

This did not help Kokushibo’s feelings of being inferior and although he cut his brother in half, he did not feel satisfied with killing him.

Kokushibo on Death

After living for 480 years, Kokushibo was finally defeated by one of the Hashira, Gyomei. Gyomei was assisted by Muichiro, who is actually a descendant of Kokushibo, and a handful of other fighters.

It was in his moment of death that Kokushibo realized that his desire for strength, his jealousy of his brother, and his fear of dying, led him to make the mistakes he made. He did not become the powerful samurai he once aspired to be, and he had forsaken all that was good in himself.

His final words were quite heartbreaking, revealing the truth of his heart: ”Yoriichi… I just wanted to be you.”

What is Kokushibo’s Personality Like?

What is Kokushibo’s Personality Like?
Source: YouTube

Not too much is known about Kokushibo’s true personality. He is a reserved and mysterious character. However, we do learn that he is quite punctual, and enjoys following the rules he is given. He also puts a lot of value in the hierarchy of the Twelve Demon Moons, perhaps something that remained with him from his days as a Hashira.

Overall, Kokushibo was a humble demon, and he wasn’t scared to admit it when he failed. Of course, this did not apply to his biggest failure in life—not becoming a good samurai as he dreamt of being as a child.

Kokushibo was also very loyal to his leader, Muzan. Almost everything he did was done to help Muzan fulfill his goals.

Still, Kokushibo was a cold character who could be quite harsh with his words. His threats were also always cruel and very serious, and he demanded absolute obedience.

When faced with his descendant, Muichiro, Kokushibo did show some warmth, and he commended the youngster’s skill and resolve. The compliments can be taken as narcissistic pride, though.

How Old is Kokushibo? 

Kokushibo was more than 480 years old when he died, and his appearance was that of a man between 17 and 24. 

How Tall is Kokushibo?

Kokushibo was 6’3”, which is 190cm, and he weighed 205 lb or 93 kg.


Kokushibo's abilities

Kokushibo was a very powerful and skilled swordsman, and he is considered one of the strongest members of the Twelve Kizuki. Kokushibo was the second strongest demon in the series, only outranked by Muzan himself.

He was a well-trained Demon Slayer, and his prowess increased after he decided to become a demon.

Demon Abilities

As a master swordsman, Kokushibo could defeat his foes with ease and almost never lost a fight. His immense speed could be seen when he was able to outpace Muichiro’s Breath Techniques and even the Mist Hashira had to admit being in awe at the speed he witnessed.

Kokushibo also had amazing physical durability, which was seen in action when Gyomei used his axe and flail to attack both sides of his neck without success.

Demon Slayer Mark

Kokushibo had the special mark that awakened Demon Slayers get, which is similar in appearance to Demon Marks. However, this mark is associated with a curse which means the marked person will die at the age of 25.

Kokushibo was not bound to the curse after he became a demon, but he was still enjoying the perks of the mark—enhanced strength and speed.

Transparent World

Much like Tanjiro, Kokushibo has the ability to see the ‘transparent world’, and he uses his many eyes to do so. As a result, he has an amazing and kinetic vision that lets him see the blood flow, joint movement, and muscles of his foes. This let him predict the attacks and movements of anyone he faced.


Kokushibo had enhanced regeneration, which allowed him to regenerate limbs and parts of his body with ease. This could be seen in his fight against Gyomei when  easily regenerated his ear and arm.

Demonic Transformation

He also had the ability to transform into a monstrous form that resembled a spider. This, we assume, enhanced his abilities greatly.

Telepathic Communication

Kokushibo was also able to communicate telepathically with Muzan because he ingested some of his blood. The two were able to have full conversations while being very far away from each other.

Blood Demon Art

The specific name of Kokushibo’s demon art is unknown, but it was this ability that allowed him to use some of his flesh and make the katana that he uses in battle. The blade, which can regenerate, has many eyes on it, and there are also eyes on the handle and guard to give him better vision range.

Moon Breathing

Kokushibo used a Breathing Style in battle and his Moon Breathing was one of the most lethal sword styles developed. 

First to Sixteenth Form

Kokushibo also had 16 forms that he used when fighting, all of them powerful and deadly.


Kokushibo and Muzan

His relationships with those around him were distant and cold when he was a demon, though we can assume he had a good relationship with his children and wife until he abandoned them. Kokushibo’s relationship with his brother was complicated, though we can gather that he did care for him until his death as he held on to the flute he gave Yoriichi.


Kokushibo is one of only two known Demon Slayers who became demons later in life. His past is a dark and rather sad one weighed down by jealousy and an inferiority complex. Still, he was a powerful character—skilled as a human and almost undefeatable as a demon.