Maybe Tamagoyaki, wrapped in nori on a bowl of rice, maybe with a side dish of miso....
dangit, now i've made myself hungry.
that's maybe what would be served on a weekend? unless you get up REEELY early on a school day, it would probably only be served on weekends.
And, most japanese high-school students make their lunches, right? they probably have to get up early anyways.