Hi, it’s Junko from Japan. A Kanji symbol on the back of the Demon Slayer Corps uniform reads METSU and means “annihilate” and “destroy” in Japanese. Here’s the image for it.
The left part with three dots represents “flowing water” and the right one stands for “burning fire.” The whole symbol shows that the water is trying to extinguish the fire, which makes the meaning of “drive something into extinct.”
It’s interesting that the METSU symbol has its origin in “water” and “fire.” Needless to say, it reminds us of the Water Breathing and Dance of the Fire God of Tanjiro!
This is the same character as METSU in KiMETSU no Yaiba, the original Japanese title for Demon Slayer.
KI = Oni, Japanese demon
METSU = annihilate, eliminate, destroy
These Kanji letters make the word KIMETSU mean “demon slayer.” The word KIMETSU doesn’t exist and it’s a coined word by the author of Demon Slayer.