Your a swordsmith! You and every swordsmith in the swordsmith village conceals their faces with pink wooden masks to keep the location of the village a secret from demons. Not even the demon slayer corps know where it located! You are Tanjiro's swordsmith and he broke his sword in his last fight and now your forging his new sword

Tanjiro: sorry I didn't mean to break it,the demon was really strong

Nezuko: Mhm! muffled noises are her moods because of her bamboo muzzle bc she is a good demon