Something really important for the bento boxes, because it's very true to Japanese tradition, is to follow seasonality. It's good that you go to the market, you find the vegetables that are in that season. First of all, because they are going to taste great . Second, they are going to be cheaper, because it's not flown in from another country or another region. The third great thing is that, according to your local farm market, you are supporting your local farmers. So, always make sure that you are putting together a bento box any of the ingredients that you are choosing to put in, they need to be from the season that you are in.