Just to help give a little cultural context that isn't necessary but I've always loved Japanese culture and so I find it interesting. They have been mentioning "hanafuda" like earrings. Tanjiro's earrings look like a traditional card game played in japan called hanafuda and usually have beautiful traditional Japanese artwork on them depicting the seasons, animals, and other plants and scenery. The cards and game also has a close tie to traditional Japanese poetry and haikus giving it a bit more of a spiritual meaning. As for the balls or "temari" the one demon throws around also have traditional significance and was a folk art form made with embroidery back in Japan and china's histories. They were used as gifts to show loyalty and deep friendship or as parental gifts but also as toys and games would be played similar to the games played with hacky sacks in the west. Traditionally a Temari would be a new years gift from parent to child and would have a piece of paper with a wish on it that is placed inside the ball upon being crafted giving them more of a sentimental value. In this representation, the reason it gives off a faint bell noise is because alternatively they would be filled with a small amount of rice or bell(s) and were basically noisemakers for kids.