Most Japanese primary school students' lunch boxes are made of various rice balls, and they are beautifully placed. What needs to be emphasized here is that Japanese rice balls are eaten cold like sushi. It is a habit to get water directly from tap water since childhood. This is very different from the situation in China. Of course, if there is fried food in the lunch box, it is heated by the school microwave oven ... but most of it is eaten directly without heating. ...