There are two advantages to the large variety of foodstuffs that go into a typical bento, or Japanese boxed lunch. Not only do they provide a diverse collection of flavors and vital nutrients, they also give aesthetically minded chefs plenty of options for arranging them in an expressive manner.
Of course, “expressive” can end up meaning very different things depending on what the bento-maker wants to express. In happy times, the result might be fun and playful chara-ben, boxed lunches that resemble popular fictional characters. But on the other end of the spectrum lie shikaeshi bento, “boxed lunches of revenge” that are as spiteful as they are creative.