ricecooker onigiri

Hi! I just purchased a ricecooker so I can make my onigiri fresh in the morning, instead of making a whole batch and freezing them. Now I'm wondering whether or not I have to wrap them in clingfilm while still hot when I make them fresh or not. Or if I can just put them warm in a box (with just the onigiri, nothing else in it). Can anyone help me out? Thanks!