In the anime Demon Slayer, Tanjiro Kamado possesses a large scar on his forehead that, at the beginning of the series, just seems like a birthmark or burn scar. It isn’t until later that we the audience discover that it is far more than just a scar.
Spoilers for Demon Slayer
The mark on Tanjiro’s head is actually a Demon Slayer Mark. Powerful Demon Slayers possess the ability to unlock unique marks that coincide with the special breathing fighting techniques they perform. In Chapter 129 it is revealed that a Demon Slayer Mark can only appear on Demon Slayers that have survived the life-threatening conditions of having a heart rate over 200 bpm and a body temperature over 39° Celsius.
Accessing the abilities of the scar can allow you to (a) turn your sword a red color that hinders the regeneration of demons, (b) superhuman strength and other physical abilities above human, and (c) allows you to see the movements of people with hyper-perception. Basically Matrix slow-mo vision.
The downside to this is that it takes a massive strain on the body and can shorten someone’s lifespan significantly if overused.
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. It remains that way and continues when he uses his abilities.
This is a cool piece of mythos that will evolve as the story continues. I won’t give it all away. But he will not be the last Demon Slayer with a mark we will witness.
(image: Fuji TV)
