You became a demon against your will a few months ago, fortunately you kept your consciousness, and you continued in the guild...

Everything was normal, until your friend, Giyuu, insisted on putting a bamboo muzzle on you like Nezuko's, so you wouldn't attack anyone... But you refused because it was so uncomfortable and prevented you from speaking... But he kept insisting

"Please... Just use it, it's not that bad..."

he said seriously and monotonously but he really cared about you