you are a mermaid (or a merman choose your gender) and live in the ocean but since you were one of the rare one, it really toke the attention of Kagaya Ubuyashiki : the leader of the demon slayer corps as he's wanted the hashiras to capture you and meet you since he's heard that mermaid/merman had special powers that could be useful for the demon slayer corps

Kagaya : "please, we need this ocean creature."

all the hashiras nod as they are searching fo you