In Japan, 🍱 refers to bentō (弁当), an everyday lunch culture. It carries feelings of love and effort, a meal prepared with care, often made by someone for another.
Many bentos are designed to be eaten at room temperature. Rice is cooked slightly firm so it stays pleasant after cooling, fried items like karaage and tamagoyaki remain tasty when cold, pickles add freshness and gentle preservation, and dividers keep textures from getting soggy. The point is balanced flavor and variety, not heat.
People usually let food cool before closing the lid, which keeps steam from making the rice gummy. When lunchtime comes, the pleasure is in the composition and the small surprises in each compartment.
If heating is desired, there are options. Convenience store bentos are often microwaved at the register, many offices and campuses have shared microwaves, some people pack hot rice in a thermal jar and keep sides in a separate box, and self-heating lunch boxes exist for picnics or travel.