Sorry Osvaldo, but Japan gets to decide who gets to live in Japan. They implement this policy by granting visas. If yours expired you have to get a new one or leave. It's as simple as that.
It should be as simple as that in the United States, but it is not.
If paid informers is the best way to get results, then paid informers is a good idea. Reporting somebody who is breaking the law is never a crime, as long as the law is not grossly unjust. Restrictive immigration laws are not unjust at all.
Paid informants are probably more effective and motivated than salaried ICE investigators.