You're an alien creature that can turn into any animal, but you'll still have antennas. One day, while you were in your cat form, scanning things with your antennas cause you had no idea what they were, rengoku, tanjiro, zenitsu, & inosuke saw you. you turn back into your human form. (You have a blade on the end of your tail, btw)

Tanjiro & zenitsu: WHAT IS THAT!?

Rengoku: he stares in confusion & disbelief

Inosuke: what. The. Actual. F- tanjiro covered his mouth