Cute idea for kids.
Onigiri is a rice ball wrapped with nori and filled with pickled fruits vegetables or meat that made rice more convenient to pack in a lunch box and take out. It isn't always a ball though and comes in various shapes.
A very cute omelette rice lunch
How to Make Rilakkuma Omurice (Recipe) リラックマ オムライスの作り方 (レシピ)
Omurice ~ Rilakkuma
curry and rice prince
anpanman mini pancake sandwich