Yoriichi Tsugikini. Yoriichi Tsugikuni is the strongest demon slayer character to have ever existed in the series. He is also the only person that Muzan was ever afraid of. He invented the original breathing styles that later branched out into the ones that Harshiras use to date.
1 Kibutsuji Muzan
In the anime, little is known about Kibutsij Muzan and his powers, other than he is the Demon King and creator of all demons. He is both respected and feared by his underlings and is the sworn enemy of the Demon Slayer Corps.
Shinobu Kocho is a capable Demon Slayer whose worthy of being the Insect Hashira. That being said, she's arguably the weakest Hashira when it comes to pure strength.
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.
Does Tanjiro have the skills to become a Hashira? Although Tanjiro remains at the fourth bottom of the hierarchy in the Demon Slayer Corps, he has always been strong enough to become a Hashira. Just the fact that Tanjiro has a fully developed permanent Demon Slayer Mark is a testament to his skills.
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.
In conclusion, Tanjiro will not be able to kill Muzan by himself since the Demon King is far superior in every aspect of combat. The manga has shown fans the singular way that Muzan could be bested and it was only due to the collective efforts of Demon Slayer Corps members.
Not only that, but his Muzan-like Blood Demon Art made him more powerful than all demons as well. Towards the end, Yushiro, the traveling companion of Tamayo, mentioned that Tanjiro had “tremendous potential” as a demon and would have been stronger than Nezuko and Muzan.
1 Giyu Tomioka, the Water Hashira
His personality, while characteristically stoic, is also protective and surprisingly passionate. Despite Shinobu's claim that Giyu isn't well-liked by the other Hashira, he may well be the most popular Hashira with the fans.
1. Gyomei Himejima. Gyomei Himejima, the Stone Hashira, is the strongest Hashira in the Demon Slayer corps in terms of strength and swordsmanship. He is the only person who uses spiked flails and an axe instead of standard swords to kill demons.
If Zenitsu fought Akaza with his plethora of Thunder Breathing techniques, the latter wouldn't have the time to regenerate his limbs.
Towards the final arcs of the manga, Tanjiro is mortally wounded and dies during a fight with the Demon King Muzan. Though Muzan is also seriously injured, he uses the last of his powers to turn Tanjiro into a demon.
There is no doubt that Nezuko is faster and stronger than the base form of Tanjiro. However, he can activate his Demon Slayer Mark and happens to be a user of the Breath of the Sun. This gives him an edge because it is one of the series' strongest and most efficient breathing techniques.
Anne was a kind and loving soul and was described as the only person that Muzan had truly loved, besides his three daughters.
Some believe that Muzan was Tanjiro's father, while others think they may have been brothers. However, there is no concrete evidence to support either theory. What is known for sure is that both men were incredibly powerful demon slayers and that Tanjiro looks up to them both as role models.
(Spoilers from the Demon Slayer anime ahead!) 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.
The Wind Hashira has one of the saddest backstories in Demon Slayer. His mother had turned into a demon and had killed five of his siblings. He was forced to kill his own mother in an attempt to save his only remaining brother, Genya.
Tengen Uzui
He is the fastest Hashira, and the second physically strongest. Obviously, then, Tengen Uzui is rather proud. He is demanding, fussy, boastful, and prone to selfishness. But he is also ultimately kind and caring, with great love for his three wives as well as the other Hashira.
5 Hashiras who end up dying in Demon Slayer (and how it happens) Demon Slayer has showcased many characters that vary in personality, strength, and overall combat abilities.