I think the starting one is the one i meant. It doesn't show up a option for me to use it.
it seems to be a bug that the developer still haven't fixed. You can get a new outfit in the game, like a Bunny costume, but it is equipped automatically. Then you can only change it to the outfits that are available.
But to have the default outfit available you have to beat the final boss with the corresponding class. Otherwise you can't change clothes