Japan is famous for its ingenious (or sometimes, plain wacky) inventions, many of which don't translate into other cultures - or haven't yet, but should. Among the latter, I count the heated toilet seat, the self-filling bathtub, and the rice thermos. My own rice thermos is pretty in pink, just the right size to hold a Laura-sized serving, and keeps rice hot from the rice cooker at least lukewarm till lunchtime.
There's a rubber band around the inside of the lid to seal in moisture and heat. It does make a bit of condensation, but that's soon absorbed back into the warm rice. Though I'm happy to eat cold rice on days when I don't have a fresh-cooked batch in the morning (I make 6 servings at a time in my rice cooker, saving the extras in the fridge) it tastes much better, and the texture is much softer, when warm.
My thermos actually came as part of a lunchbox set, and the cloth lunchbox itself aids in the insulation. The padded divider panel velcros to the side and can be folded back if I put a whole bento box, instead of the thermos and the two smaller containers for okazu, side dishes, that came with the set. Interestingly, the Japanese concept of side dishes includes both meat and vegetables - in other words, everything else is considered a side to rice, the main course. Take that, Atkins dieters!