It's a cat burglar!

:v

Well, Katzix is a thief and it is him that does most of the stealing/sneaking around. He does have an alternate uniform for a night raid/robbery because the other is better for fighting.

This costume wasn't originally planned to be a full body suit. It was planned to go down a bit close to the knee with no arm and eye mask. However, since Cat Noir is a thing now, making it a full body suit turns out to be a whole lot better. That and we know cat boys wear it better than cat girls.