Kokushibo – Upper Rank 1 Kokushibo is one of the strongest demons in the anime, only second to Demon King Muzan. Before turning into a demon, he was a part of the
Who is stronger than Muzan, the original Demon King? The only character who was stronger than Muzan was Yoriichi. He almost beat Muzan before splitting his body into 1800 parts in an attempt to escape. He escaped successfully and managed to fuse back into a single body after a while.
It's important to understand exactly what a Demon King is. For centuries, Muzan was the Demon King because he was the first of his kind, and it was through him that all other demons were created. As Muzan was dying, he passed his essence into Tanjiro, granting him more than just incredible power.
The warrior Muzan feared was a swordsman named Yoriichi Tsugikuni. Yoriichi was the only slayer before Tanjiro who came close to killing Muzan, and the flashback of their fight occurred in Chapter 187.
1 Muzan (Demon Slayer)
Without that antidote, it would have been impossible to kill him. So despite all her strength and humanity, Nezuko would have easily lost to Muzan.
Curse of Kibutsuji
This curse besotted any who partake of Muzan's blood must be careful. The curse prevents Muzan's name from being spoken aloud, and any who do will meet a horrible demise. One demon, Susamaru, faced this reality when battling Tamayo.
Yoriichi Tsugikuni was the first Demon Slayer and also the one who invented Breathing Techniques in the first place. Yoriichi was born with the Demon Slayer mark and prowess in swordsmanship. His powers were beyond comparison as he defeated Muzan once and had him on the verge of death until he managed to escape.
Muzan is shown to have a positive master-servant relationship with Daki, as the young Demoness seemingly worships and admires the Demon Progenitor immensely, fervently hanging on each and every one one of his words and doing her absolute best to accomplish the tasks he gives her.
How Doma became the worst demon in Demon Slayer. Almost every creature possesses emotions, be it anguish, sorrow, happiness, or even fear. However, in the case of Doma, he doesn't feel a thing. During his childhood, his mother stabbed his father to death for cheating on her and, later on, took her own life.
After various battles within the Dimensional Infinity Fortress the remaining Upper Moons are killed by the hands of various Demon Slayers. The last member, Upper Moon Four Nakime, ends up being killed by Muzan Kibutsuji himself to stop the Dimensional Infinity Fortress from being controlled by his enemies.
Many Kimetsu no Yaiba fans deduce that Yoriichi is Tanjiro's father, but that isn't the case. However, Yoriichi is responsible for teaching Tanjiro's ancestors the Hinokami Kagura, which has been passed down for generations.
Muzan Kibutsuji's main weakness is sunlight, as seen when Gyōmei destroyed his head and he still couldn't manage to regenerate it. He tried to overcome this by devouring Nezuko, but that failed. He also has a weakness to Nichirin Blades, as they are the only way to kill him.
Yoriichi defeated Muzan in an instant, but he had a question for him before eliminating him, which allowed Muzan to escape.
Tanjiro decapitates Akaza with the Hinokami Kagura: Setting Sun Transformation. Akaza was bewildered, wondering how Tanjiro did not have any fighting spirit, comparing this feeling to fighting against a plant. He acknowledges that Tanjiro surpassed his speed.
Don't go! DON'T LEAVE ME HERE! Muzan speaks his final words as he loses control over Tanjiro.
In the first few arcs of the series, the identity of the demon that killed Tanjiro's family was a mystery. It is later revealed that it was none other than the series' main antagonist, Muzan Kibutsuji.
Thus, Muzan created demons for hundreds of years even when he didn't want to turn someone. Since he didn't know anything about the Blue Spider Lily medicine, he needed others to find the plant for him by happenstance. This is the general reason why Muzan turned Nezuko into a demon.
In a nutshell, Muzan, being the progenitor of demons, is not scared of Doma. However, he is irritated by his inability to decipher Doma's thoughts and feelings, which is the ultimate control he has over all of his creations. Upper-Rank Two: Doma is a nihilistic maniac and a misanthropic cold-blooded demon.
Enmu's passionate praise about Muzan led many fans to think that Enmu is extremely devoted to the demons and worships him with something close to infatuation. He likely wanted to be an Upper Moon to be closer to Muzan, or to not be seen as weak and worthless in Muzan's eyes.
It is unclear if the curse branded to her by Muzan got lifted or not, but she can't speak a word after turning into a demon, and always has a muzzle in her mouth. As Nezuko can't speak Muzan's name out loud, she can't be affected by the curse.
If Zenitsu fought Akaza with his plethora of Thunder Breathing techniques, the latter wouldn't have the time to regenerate his limbs.
With this in mind, if Nezuko had also been murdered by Muzan, Tanjiro would have no reason to be empathetic toward demons. Her transformation gave him a perspective of both demons and humans, but without Nezuko becoming a demon he would have no reason to take their feelings into account.
Towards the end of the Demon Slayer manga, it took the combined efforts of multiple Hashiras including Tanjiro, Inosuke, Zenitsu and the poison made by Tamayo to be able to defeat Muzan. Even then, the group barely managed to kill him and a lot of lives were sacrificed in the process.