Warning: contains major SPOILERS for the plot of Demon SlayerOne of the most fascinating attributes of Demon Slayer's Tanjiro Kamado is his facial mark, because of its link to a long-forgotten secret that goes to the heart of the origins of the Demon Slayer Corps and their centuries-long battle against the first demon Muzan.

Since the manga's first chapter, Tanjiro is depicted with a large reddish blotch above his right eye that was initially explained as a burn scar he got saving his little brother from a pot full of hot coals. However, after a fight with the Hand Demon in Chapter #7, Tanjiro suffers an injury near the scar that required bandaging. Surprisingly, when the bandage was removed in Chapter 10, the blotch subtly changed into a dynamic flame-like shape. For any fan who noticed, no immediate explanation was given for the change. Later, after a battle with the Lower Rank Five Demon Ru, the scar changes again, and then again after a fight against Upper-Rank Six Demon Gyutaro. It's only then that fans learn the scar is actually a "Demon Slayer Mark" - a special mark that manifests in a select few Demon Slayers after they reach a specific level of physical and mental stress, unlocking super-human abilities.

Tanjiro's Mark Can Unlock the Power Of The Hinokami Kagura

While these attributes of Tanjiro's scar are interesting, what's more, fascinating is how it links back to the strongest Demon Slayer Yoriichi Tsugikuni, the first person to ever manifest a Demon Slayer Mark and the originator of the super-powerful Sun Breathing Technique, who is also the brother of Michikatsu Tsugikuni, aka Kokushibo, Muzan's top-ranked Demon. Tanjiro's mark closely resembles in design, size, and location the mark Yoriichi manifested during his service as a Demon Slayer. Tanjiro and Yoriichi are not related by blood, but Yoriichi did save his ancestor Sumiyoshi from a demon and subsequently became his close friend. The two spent so much time together afterward that Sumiyoshi eventually memorized Yoriichi's Sun Breathing Kata and later recreated it as the Hinokami Kagura - a breathing style and dance that his clan performed every year as a ritual to the Fire God. The Hinokami Kagura eventually became a Kamado family tradition that was passed down from generation to the firstborn male, including Tanjiro.

Yoriichi was the first to ever show the Demon Slayer Mark, but once manifested, he was able to pass it on to others. Accordingly, Tanjiro's manifestation of the mark is most likely due to Yoriichi inadvertently passing it to Sumiyoshi in some way, who then passed it to his descendent. It manifested in Tanjro due to the "perfect storm" of his experiences facing death, training with the Demon Slayer Corps, and his tacit knowledge of the Sun Breathing Technique via the Hinokami Kagura somehow working together to unlock the mark within him. Outside Yoriichii and Tanjiro the only other person to bear a similar Demon Slayer Mark is Yoriichi's twin brother Kokushibo, who, like Tanjiro, manifested it during his Demon Slayer training with Yoriichi. Before he joined Muzan, Kokushibo was the head of the clan and one of the two best Demon Slayers of that time.

Tanjiro Shares His Mark With Two Of History's Best Demon Slayers

The only Demon Slayer Muzan truly feared was Yoriichi, who almost killed the villain in their first encounter. It makes sense, therefore, that Tanjiro's facial mark is so fascinating. Not only has its evolution unlocked powers that put him on par with the Hashira, but it also links Tanjiro to the only two brothers who were able to rise to the highest levels of the Demon Slayer Corps.