Tanjiro awakened his
In the case of Tanjiro, the mark used to be just a graze, but during his fight with the Hand Demon during the Final Selection, the mark changed. That life threatening condition altered him and afterwards, it develops into a flame-like pattern and is his new Demon Slayer Mark.
Fighting in conjunction with Tengen, Tanjiro awakens his Mark while beheading the demon. It is said that only those who have survived life-threatening situations with a heart rate of 200 bpm, as well as a body temperature over 39 degrees Celsius, can awaken their Demon Slayer Marks.
Once awakened, the Mark can disappear after a period of time along with its effects, though it can be re-activated (as seen with Muichiro Tokito and Tanjiro Kamado) by meeting the same conditions or through training to maintain the 'Marked state' to prevent it from dissipating in the first place.
To become a member of the Demon Slayer Corps, he had to clear the Final Selection. During this event, Tanjiro received a massive blow to his head from the Hand Demon that killed many of Urokodaki's students. This increased the size of his scar and changed the color as well.
In the Demon Slayer Corps, the Hashira is a group of the strongest and most reputable swordsmen who have defeated members of the Twelve Kizuki. Yet, for some reason, Tanjiro Kamado, the series' protagonist, never becomes a Hashira.
The black blade represents the Sun and is surrounded by prejudice and misconceptions, as historically every demon slayer who held it lived a short life. This could mean that Tanjirou is destined to break the pattern and set a new legend for black Nichirin blades in the Demon Slayer universe.
Later in the battle Tanjiro's left arm is severed by Muzan. After being turned into a demon by Muzan, Tanjiro is able to heal the growth on his face as well as regenerate his lost arm and other smaller injuries.
Tanjiro certainly did a lot of good with his Water Breathing techniques, but his ability to use Sun Breathing both gives him an edge in battle and allows him to stand out among the incredibly powerful Hashira he fights alongside.
During Tanjiro and the rest of the Hashiras' showdown with the Demon King Muzan, Tanjiro is mortally wounded and dies. At the same time, Muzan receives a particularly fatal lil' booboo himself. As Muzan is about to shuffle off the mortal coil, he uses the last of his powers to turn Tanjiro into a demon.
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.
Initially, Tanjiro's accuracy and strength were not up to the mark, which is why Muzan was able to avoid his attacks. However, Tanjiro accurately performed the thirteenth form and inflicted a ton of damage on the Demon King.
Demon Slayers who have awakened the Demon Slayer Mark are said to die upon reaching the age of 25. Michikatsu Tsugikuni speculated this to be because the mark exchanged the life span of its user for power.
Kyojuro Rengoku was the first Hashira to die at the hands of an Upper Moon demon, due to an unfortunate encounter with Akaza. Despite the intensity of his battle against the demon, he never manifested his mark, and undoubtedly did not even know the conditions for doing so.
Tanjirou, Sanemi and Giyuu probably all died by age 25. This has nothing to do with the eradication of demons.
During their battle, the former unleashed an attack that harmed multiple people in the entertainment district. Seeing the loss of human lives and the ceaseless destruction caused by the demon, Tanjiro's was overcome with rage, causing his eyes to start bleeding.
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 Yoriichi Tsugikuni
Yoriichi was the very first user of the Breathing Styles and he came up with Sun Breathing, a powerful breathing form that is known to be the most effective against demons.
After Doma's demise, Kanao wears Shinobu's hair pin instead of Kanae's, as the latter was destroyed during the fighting. Furthermore she loses visibility in her right eye due to unleashing the final form of Flower Breathing, even though the eye is unaffected visually.
Chapter 204 of the series takes place three months after the battle with Muzan, and gives us an update on the extent of Tanjiro's injuries. Although his demonic transformation physically restored his right eye and left arm, now that he's cured those body parts have been left unusable.
He also reveals that after Muzan's poison directly hit his eye, his eye seems to have healed but he can't see out of it. These two parts of his body were completely destroyed in the battle, and his demonic transformation only brought them back at this lesser extent.
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.
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.
1. Tanjiro's Black Sword. Of course, the one who takes the top spot in terms of the best swords in Demon Slayer is Tanjiro's black Nichirin blade.