Taking a sip of water and opening a strongly scented meal after the lights go out are both technically “eating or drinking,” but on a Japanese overnight bus they are not treated the same way.
Whether you can eat or drink on board first depends on the bus company. Some operators allow food and drinks, while others ask passengers to avoid strongly scented foods, noisy packaging, or eating after lights-out.
What tends to matter most on an overnight bus is not simply the fact that someone is eating. Passengers spend hours together in a confined space, and many are trying to sleep. Smells, rustling wrappers, spills, and leftover trash can therefore become much more noticeable than they would be elsewhere. Smell in particular has nowhere to go. Food that seems harmless during the day can suddenly make its presence felt inside a closed bus.
If the operator asks passengers not to eat after lights-out, that rule should of course be followed. But the social boundary is slightly different from the formal rule. Something with very little smell or noise that does not disturb the people around you would not necessarily be considered bothersome simply because you are eating it.
The same applies to drinks. Quietly drinking water or tea is very different from drinking alcohol with a strong smell that affects nearby passengers. Some operators specifically ask passengers to avoid strongly scented drinks or alcohol.
On a Japanese overnight bus, it is more useful to ask whether the smell, noise, or movement will reach the person trying to sleep next to you than to divide everything into “food is bad” and “drinks are fine.”
