What confuses me is that Japan is not a very immigrant-heavy country. There's no chance of someone who doesn't represent the interests of native Japanese people being elected any time soon, or ever. So why can't they pass laws codifying the behaviors they want to encourage and ones they will treat as non-assimilation? Why aren't they doing something to address misbehavior directly, making newcomers to the country prove their long-term commitment to their new social and cultural environment, or punishing infractions more harshly so bad actors can't stay in the country? Why are the only two options available to them 'do nothing' or 'blanket punish all foreigners because all foreigners are trouble'?