Inarizushi  are excellent for bento, but they can be a bit high in calories since they are stuffed with sushi rice. The original version  with a 100% rice filling has about 1/4 to 1/3 cup of rice per bag, which makes each inarizushi about 110 to 130 calories. On the other hand these inarizushi are about 80 to 100 calories per piece. The secret is in the filling.
I’ve mixed about 1/4 cup of stewed hijiki seaweed with carrots and shiitake mushrooms  to every cup of sushi rice. The recipe for stewed hijiki is here  - I just added a couple of raw shiitake mushrooms to it, omitted the fried tofu, and chopped up the carrots quite finely. I also used brown rice instead of white, for even more fibre and nutrition. An all-inarizushi bento with extra ingredients in the filling is, in fact, a pretty nutritionally complete vegan meal.
Hijiki and shiitake have almost no calories and are high in fibre and various minerals (more about hijiki ), and carrots don’t have a lot of calories either, so adding them to the rice mixture is a good thing all around. Try mixing other things into the rice stuffing too!
Inarizushi freezes very well, because the moist tofu skin protects the rice inside. Since I’ve stocked up on some Lock & Lock boxes , I’ve made batches of inarizushi and frozen them 3 or 4 at a time in 360ml boxes.
I’ve tried defrosting them in three ways:
Stewed hijiki keeps for about a week in the refrigerator, and also freezes very well. You can freeze it in small portions and then just pop a portion in a bento as a side dish, or mix it into rice, and so on. You can also mix some into a basic tamagoyaki to add texture, fibre and flavor. Here I used about 1/2 tablespoon for a 1 egg tamagoyaki .