Bento is a Japanese tradition of placing a balanced, nutritious, and flavorful meal in a portable container called a bento box. The modern bento dates back to the Edo period about four hundred years ago. Although the meal can be eaten at a restaurant, it is meant to be a sort of picnic, presented in wooden, plastic, or lacquered boxes with compartments on the inside - each one intended to hold a variety of tiny bites.
Most often, bento boxes are filled with rice cakes bound with dried seaweed, fish cakes, shrimp, steamed crayfish, pickled vegetables, or chunks of glazed chicken - all intended to be eaten at room temperature. Bento is commonly sold on trains (bento is then called ekiben), and each box can be sold for up to four hours after preparation.