What wrappers are you thinking of? The one mostly in the pictures are the linen napkin. But on the regional meals you can also see paper separating the rice from the dish. In Japanese cooking for a lot of dishes the rice is not supposed to mix with the other foods. On long flights the rice is steamed onboard and served in separate rice bowls. On short flights where it is heated together, there is a paper separator.

These are the two options I see from the pictures, if you can point to another, I'll see if I have a reason.