The sword is primarily black, but it turns crimson red when the Breath of the Sun God (strongest breathing style) is used by both
Yoriichi's bright red Nichirin sword is the most potent out of all Demon Slayers, being able to burn on a cellular level and leave scars that even the Demon King himself can't heal even after centuries.
The Yoriichi Type Zero sword is the same Nichirin katana that Yoriichi Tsugikuni carried during his time as a Demon Slayer. It is deep black in colour and changes to bright red during combat, a characteristic shared by all Nichirin swords used by the Demon Slayer Corps.
Red Nichirin Blade
Red often means intensity, and in Demon Slayer this is no different. The red sword represents Flame and Kyojuro Rengoku's excentric and expansive personality translates that.
Black blades are seen as a rarity, as demon slayers who wield them are doomed to die young. No wielder of a black sword has ever become a Hashira, either. However, this is all superstition.
8) Muzan hates being called pale or dead
Muzan is the most powerful demon in the entire series, and is responsible for creating all demons. For someone who considers himself to be perfect, it is natural that he will hate being called pale or dead. This is established quite early on.
Black. Toho Co., Ltd. Black is the most mysterious color of all the blades, and is held by the main character, Tanjiro. It is a rare blade and represents the sun; it also holds a theory that the demon slayers who own this sword are not to live a long life.
Even Muzan himself stated that the red Nichirin blade has no effect on him if he was not drug by tamayo. Just yoriichi's red nichirin blade had a effect on him. So Yoriichi just need to cut him down as much as possible so he can't regenerate himself and just fell apart.
As a Demon Slayer, Yoriichi Tsugikuni carried a fairly standard Nichirin katana — deep black in color, that changed bright red during combat. This is the sword that appeared out of the neck of the doll at the end of Demon Slayer season three's second episode.
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 ...
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!)
Yoriichi lived till old age, likely due to him having been born with the mark and thereby avoiding the curse altogether. Gyomei on the other hand did not activate his Mark until he was already older than 25. It was speculated that when he awoke his Mark during battle that he would likely die within hours.
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.
Tanjiro Got the New Sword from Yoriichi Zeroshiki | Demon Slayer Season 3 [104-105] - YouTube.
As another testament to his godlike movement speed, Yoriichi Type Zero, the robot doll modeled after him used by Demon Slayers to train, was built with 6 arms because 2 arms alone couldn't replicate Yoriichi's movements.
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.
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 Demon Slayer Corps alongside his brother Yoriichi Tsugikini.
Obanai was able to slash his Nichirin Sword past Muzan's neck, but to no avail as the moment his blade cuts Muzan's neck it regenerates instantaneously. This confuses Mitsuri to the point where she doubts that Muzan is not being cut down, whereas Giyu knows that Muzan is being cut but regenerates his wounds instantly.
However, the scar changed its appearance during the Final Selection when the Hand Demon gave Tanjiro a major blow to the head. The blow not only increased the size of his scar but changed its colour as well. The scar changed even more when Tanjiro fought against Gyutaro and Daki during the Entertainment District arc.
This is unsurprising, as Tengen's sound breathing was based on thunder breathing to begin with. They are also shaped more like cleavers than traditional katana, and feature a single large hole in each blade, possibly to allow Tengen to hook unto enemy's weapons or bodies.
Of course, the one who takes the top spot in terms of the best swords in Demon Slayer is Tanjiro's black Nichirin blade. Although Tanjiro started out as a Water Breathing user, his Nichirin sword turned black instead of blue, and that surprised him because black swords are said to indicate bad luck.
It is revealed that Muzan's true fear of dying and immense desire to live and survive was due to him being born "dead," where his heart would constantly stop in his mother's womb and was assumed stillborn until he fought to breathe before his cremation.
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 he neutralizes Tamayo's poison and emerges from his flesh cocoon, Muzan's hair grows in length and turns white due to Shinobu's poison accelerating his age. He also grows numerous mouths all over his limbs, each one lined with a set of incredibly sharp fangs.