Kokushibo pursues strength and greatly desires to be the strongest, causing an inferiority complex towards his younger brother. At first, he thought of himself as superior and pitied Yoriichi, but after witnessing his strength he became jealous and began to hate his brother.
He was so afraid of death that he allowed himself to become a Demon and therefore immortal. This makes him one of the few known Demon Slayers to defect and turn to become a Demon. In doing so he abandoned a wife and two children, though unlike many new demons he did not slaughter the vestiges of his human family.
Yet despite his chronic envy, Kokushibo could never truly hate his brother. Upon striking Yoriichi's corpse, he realized that he had inadvertently broken the flute he had gifted to him as a child.
Kokushibo's disgust turned to fear upon seeing that Yoriichi still was the same capable and powerful warrior from before. He told his brother when he was to attack and soon struck, slicing through his neck without Kokushibo able to even draw his blade.
He still smiled through that to show his love for his brother. In fact, he was the first person that taught Yoriichi what the idea of “love” is. Sadly though even with six eyes, Kokushibo couldn't see the love that Yoriichi had for him until the end.
Enraged by the feeling of inferiority, he slashed Yoriichi's body in half, but inadvertently broke the flute he gave him as a child. Seeing that he still thought highly of him even after his transformation, Kokushibo couldn't help but shed a tear.
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.
As the battle reached its climax, Tanjiro was able to knock the doll's head off and discovered that the mechanical body contained a mysterious sword. Fans of the manga will recognize this sword as the one carried by Yoriichi Tsugikuni himself.
But if we are talking about the human form, then it's a big fat NO, because Tanjiro has just mastered the Sun Breathing whereas Yoriichi is the inventor of it, also he's way more powerful and holds an unfathomable battle intellect, larger than any Demon Slayer in history, so in conclusion, no one is remotely close to ...
Does Muzan have a favorite demon? Despite the fact that Muzan. is always shown to have disdain for his creations, Muzan does in fact have a favorite. On that list is Naki, made due to a convenient blood demon.
However, despite this immense jealousy, spite, and the outright hatred he harbors for Yoriichi, he still deeply cares for his brother, as seen when he was touched by Yoriichi treasuring the handmade flute he had made for him as children; Kokushibo sheds tears over his brother's death, and even goes as far as keeping ...
Kokushibo's stoic and silent disposition. Kokushibo was reserved, silent, and aloof, maintaining an aura of unnerving tranquillity and mystery that compliments his position as Upper Rank One. He rarely speaks; when he does, he talks in a slow and emphatic sense that gives more gravitas and authority to his words.
Kokushibo holds immense respect and loyalty towards Muzan and unlike other demons who often time act recklessly, he only works towards fulfilling his master's goals. Apart from other demons, Kokushibo assimilated a heavy dose of Muzan's blood, which makes him the strongest of all Upper Demons in Demon Slayer.
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.
Furthermore, Doma is regarded as the coldest and most obnoxious demon. He frequently behaves carelessly around Muzan, which he even hates. All these aspects, as well as Doma's lack of sincerity, irresponsibility, and complete maniac-like nature, fuel Akaza's hatred for him.
However, after his death, he accepted that he is wrong and that Heaven and Hell actually do exist. Doma also displayed what arguably is his first true emotion, love, when he proclaimed his love for Shinobu after finding her cute.
5) Yoriichi
That being said, there is no doubt that he is the strongest character in the series. Case in point: he was the only one who could single-handedly take on Muzan and drive him to a corner. Yoriichi would be able to defeat every single Hashira on this list without breaking a sweat.
Rimuru Tempest becomes a God towards the end of the series and can travel back in time and travel between worlds. His space-time abilities alone would be enough to beat Yoriichi.
The sword is primarily black, but it turns crimson red when the Breath of the Sun God (strongest breathing style) is used by both Tanjiro as well as Yoriichi.
So now, Tanjiro, the protagonist of the Demon Slayer series, has access to a sword that belonged to the best swordsman to have ever lived. This sword was in bad condition, but Hotaru Haganezuka took it upon himself to restore the blade to its former glory.
Tanjiro's connection to Yoriichi is not through blood relation, but through their similar appearances, which is due to the divine nature of Sun Breathing. (Also Read: Did Demon Slayer hire a Bollywood director for Season 3? Fans speculate!)
Is upper rank one Tanjiro's father? No, they are not related. Tanjiro, by PURE COINCIDENCE, heavily resembles Yoriichi Tsugikuni, the creator of Breath swordsmanship, the only other person to use Sun Breathing, and the only person Muzan ever feared.
Tanjuro Kamado a recurring flashback hero from Demon Slayer : Kimetsu No Yaiba. He was the husband of Kie Kamado, and the father of Tanjiro, Nezuko, Takeo, Hanako, Shigeru, and Rokuta. Tanjuro was a flame dancer who used to dance the Hinokami Kagura during the winter.