Total calories (approx): 355 (how calories are calculated) 
Time needed: 5-10 minutes in the morning, just to pack everything in the bento box
Type: Japanese, chicken!
This is a bento that uses one of the chicken recipes I’ve posted, little chicken dumplings stewed with carrots  (tsukune-ni). The recipe takes about 20 minutes to cook, but since it is a bid fiddly it’s best made in advance. It keeps for 2-3 days in the refrigerator, and can also be frozen quite successfully. What I usually end up doing is making enough for dinner, with ‘planned leftovers’ for the next day’s bento. The soft dumplings go marvelously well with rice.
Note that I have use the higher-fat dark meat of the chicken here, but the bento still clocks in under 400 calories since no added oil is used for cooking. For bigger appetites, just pack more of everything.
You can also boil the green beans (or other green vegetable) the night before. Since the stewed dumplings have lots of flavor I don’t add any to the green beans; instead, I pack it under the dumplings, and drizzle a bit of the stewing liquid over both.