If you are a demon slayer fan, you will be curious to know if the king and father of demons, Muzan Kibutsuji fought the favourite of the upper moon series, Michikatsu Tsugikini, known as Kokushibou, who holds the rank of upper moon one.
He is also a brother of Yorricchi Tsugikini, who created the sun breathing.
Then read this article further because it will eventually have spoilers, so keep that in mind.
How Strong is Kokushibo Compared to Muzan: The Relationship Between Muzan and Kokushibo?
Their relationship in the series is one of the most trustable partners because Muzan thinks of him as his Business partner.
Kokushibo is also loyal to him and will never betray him.
So the situation like they will fight each other will never come.
But let’s assume for today, but first, let’s see about their Backstory.
Kokushibo’s Backstory: Why did Michikatsu Tsugikini become a Demon Kokushibo?
Michikatsu Tsugikini was born in a samurai family, and he had a twin brother named Yorricchi Tsugikini.
Both of them were fond of becoming samurai, but the problem was only one could become a samurai, so Yorricchi sacrificed his dream.
Then Michikatsu started training to become samurai.
Once while taking lessons on swordsmanship, Michikatsu and Yorricchi were supposed to fight their sensei.
Yorricchi had almost defeated the master, whereas, after the hard training, Michikatsu even cant touch his master.
His father heard this news, and he chose Yoricchi as a successor.
Yoricchi was aware that his brother Michikatsu was passionate and loved to become a samurai.
Yoricchi wants to see his brother happy at any cost. Because Yoricchi loves his brother so much that he can do anything for him.
So Yoricchi sacrificed his dream for his brother and left home.
When a year later, a demon attacked Michikatsu and at that time his samurai skills didn’t help him, he was saved by his big brother Yorricchi who had become a demon slayer and had created a new breathing style called Sun Breathing.
Now slowly, Michikatsu developed greed for power, and he also started practising sun breathing, but he could not endure it, so he created his breathing of his own and named it moon breathing, but it was not as vital as the sun breathing.

But he wanted to be stronger, so he decided to become a demon because if he became a demon, he would be stronger and gain immortality.
So after becoming demons, only sun breathing users could be able to kill him, so Muzan started killing all the sun breathing users from every era.
For more convenience, they created twelve Kizukis, in which Kokushibou was awarded the first rank because he had become powerful.
How Strong is Kokushibo Compared to Muzan: How Much Powerful is Kokushibou?
Kokushibo is an upper moon, so of course, he is powerful, so let’s see about some events of his to calculate his strength.
1] Akaza offers him to fight for upper moon one rank: When Akaza offers him to fight, Kokushibou stomps him and leaves him alive it was the first time Akaza had seen his strength, and he was shocked and feared at the same time.
2] Akaza blows the head of Douma: When Akaza blows the head off, Douma, Kokushibou tries to stop him with some of his power and guess what? Akaza stops.
3] The fight between him and demon slayer corp in infinity castle: When 3 Hashiras Muichiro Tokitou, Sanemi Shinazugawa, Gyomei Himejima and Genya Shinazugawa, younger brother of Sanemi who eats a demon and can use blood demon art, regardless fighting hard they even can’t blow his head off the reason being Kokushibo can regenerate his head too.
The battle was fierce, but Kokushibo had the upper hand, and he quickly stomped all of them, but after some time, when Hashiras got the demon slayer mark, they became powerful Kokushibo was more potent than them.
This shows he is the most robust character after Muzan as he uses breathing and blood demon art simultaneously. So this concludes his power level.


Kokushibo vs Muzan Conclusion: Who is more Stronger, Muzan or Kokushibo?
As if we talk about strength, Muzan has monstrous and unimaginable power, whereas Kokushibou is not decisive as Muzan because Muzan has more experience and has eaten more humans than him.
Therefore, as per manga, he is known as the Demon King and is far more powerful than Kokushibo.
He fought all Hashiras, including the demon slayer corps, alone, but in his place, if we kept Kokushibou, he would have been decapitated already by them.
But Muzan almost killed everybody when he was already poisoned by Tamayo, who was making him weak rapidly.
So if there is a fight between Muzan and Kokushibo, Muzan will win it, but Kokushibou will give a tough battle against him. So the battle will be super amazing and exciting. So this satisfies the answer to the question.