What does 弁当 Bento mean?

A bento is a packed meal. The word names the meal rather than the container, which is a bentōbako (弁当箱), and English lunchbox picks up the less important of the two.

The range

At one end, a cheap plastic tray from a convenience store, eaten at a desk, entirely unremarkable. At the other, a hand-made arrangement that took someone an hour before dawn, packed so that the contents look composed when the lid comes off.

The same word covers both, which is worth knowing, because English readers of fiction sometimes assume every mention implies the second.

Why it matters in stories

Because making one for another person is labor, and everyone involved knows how much. A hand-made meal given to someone is a measurable quantity of early rising and attention, and it can be offered, refused, shared or compared in public.

That makes it dramatically useful in a way a sandwich is not. A character who makes one for someone has done something; a character who receives one has been told something; a character whose own is plainly bought has a small fact about their household on display beside them at lunch.

The elaborate kind

There is a whole practice of arranging the contents to depict characters, which parents do for children and which has become a minor competitive art. It is decorative and it is time-consuming.

Why the box matters

Because the container is designed around the problem. Compartments keep components separate, the arrangement is meant to be seen when opened, and the food is chosen to be edible at room temperature hours later.

A packed lunch in English is defined by when it is eaten. This is defined by having been assembled to survive the interval and to look intentional on arrival, which is a different design brief and produces different food.