When someone is speaking loudly or wearing a strong fragrance on a train, in a restaurant, or in another shared space, many Japanese people will not immediately confront the person. They are more likely to move to another seat, change train cars, or create some distance if they can.
Silence does not mean that nobody is bothered. Some people may cough pointedly, give the person a cold sideways glance, or even click their tongue to show their irritation indirectly. A sideways glance can do a surprising amount of talking.
If the person does not notice, many people will still choose to leave rather than start an argument. The behavior may be unpleasant, but confronting a stranger can create an even more troublesome situation. They are not accepting the behavior. They simply do not want to turn it into a personal conflict unless they have to.
When moving away is difficult, it is usually better to speak to someone responsible for the space, such as a member of the restaurant staff, a station employee, a train conductor, or hotel staff. Loud behavior can sometimes be addressed directly by staff. Strong scents are more difficult.
Noise is an action that someone can usually change. Smell may involve perfume, body odor, a health condition, or another personal circumstance. Telling a stranger that they smell bad can easily feel less like a request about their behavior and more like an insult directed at the person.
For that reason, if a smell is making you uncomfortable, asking, “Would it be possible for me to move to another seat?” will usually cause less tension than asking staff to speak to the other person about it. The aim is often to create distance rather than decide publicly who is at fault.
A foreign visitor who politely says, “Could you please speak a little more quietly?” is not automatically being rude. Japanese people also sometimes confront someone directly when the disturbance is serious. If the person realizes that they have been speaking too loudly, a normal response would simply be to apologize and lower their voice.
The difference is mostly in when people choose to speak. If the problem is only mildly annoying, many Japanese people will try moving away or asking staff for help before addressing the person themselves. Directly asking someone to stop is possible; it is simply less likely to be the first step.
Dangerous behavior is a separate matter. If someone is drunk and harassing passengers, shouting aggressively, or creating a risk to others, do not quietly endure it. Contact staff or the police and ask for help. Avoiding unnecessary confrontation does not mean ignoring a dangerous situation.