Does anyone know what kind of IC card is being used even tho is has 0yen in it?

Okay, so, I saw a man in front of me used an IC card to exit out of the train station but instead of the one like mine where it showed the amount deducted and the remaining balance, I saw 0 yen on both but they still got passed… Is it some kind of prepaid/postpaid or pay later type of IC card? Or what is it? I'm quite confused. How 🤨

by notyouladybbm