The Yoriichi Type Zero sword is the same Nichirin katana that Yoriichi Tsugikuni carried during his time as a
Standard Nichirin Katana: Yoriichi carries around a standard sized and shaped Nichirin katana that is deep black in color, but changes bright red during combat. His katana's hilt is circular shaped with 4 slight indentations, with a black center and a golden border.
This tradition came some time after the creation of the sword that Tanjiro and Kotetsu found inside the Yoriichi Type Zero, which only had the Slay ( 滅 めっ , Metsu?) on it and was created for the sole purpose of annihilating demons.
The strongest Demon Slayer to have ever lived, Yoriichi Tsugikuni, similar to Tanjiro, had one of the rarest sword colors out there. His Nichirin sword is of an obsidian black color, which is a bad sign in the Demon Slayer world that would signify a short life, however, he lived to be old.
Yoriichi Tsugikuni'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.
What is the Yoriichi Type Zero sword? 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.
Tanjiro Kamado wields a black Nichirin blade, but the symbolism of such a sword was initially unknown. 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.
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.
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.
This is the sword that appeared out of the neck of the doll at the end of Demon Slayer season three's second episode. In the manga Tanjiro has the sword repaired by Haganezuka, who he initially traveled to the Swordsmith Village to find.
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.
Tanjiro is the descendant of someone who knew Yoriichi personally and was a good friend of his as well. Sumiyoshi was rescued by Yoriichi when a demon threatened his life. Since then Yoriichi often met him and they became close acquaintances.
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!)
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 ...
In the Anime
These earrings that Tanjiro wears have an extensive history. They were originally worn by the legendary Demon Slayer Yoriichi Tsugikuni, the originator of the breathing styles that so pervade the Corps.
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.
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.
Nichirin Come in Many Colors, but Black is Strongest
Blades associated with Water Breathing typically change to a blue color, for example, while that of a user of the Flame Breathing technique would turn red.
Green Nichirin Blade
The Breathing that inspired many other techniques is represented by the green sword color. Wind is the element of the green Nichirin blade and Sanemi Shinazugawa is the one who wields it in Demon Slayer.
9 Tengen Uzui, The Sound Hashira
The Sound Hashira might have a cool character design, but his power isn't really anything noteworthy. This is especially true when compared to some other Hashira in Demon Slayer who boast truly impressive powers.
Being one of the strongest Hashira, Sanemi's sword matches his appearance. His sword is very durable and lasts throughout the series. It had no problem piercing through the box that Nezuko is held in. He fought against Kokushibo during the final arc of the manga.
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.
Nichirin swords are unique to the swordsman and are known as color-changing swords because the blade's exterior will change to reflect its user; however, a black nichirin sword is said to be bad luck -- and only two known users in Demon Slayer have weilded one.
Tanjiro is a prime example as he only became a Demon Slayer and got his black Nichirin after a demon Human Slayer-ed most of his family.