To hire someone to find a person?

Hello. Is it possible legally from abroad to hire special agency or a person to locate japanese citizen in japan? does anyone knows any such agencies & can provide an information, please?
Thx!

I'm sure you will find plenty of private investigators in Japan by Googling "private investigator Japan". They will be able to answer all of your questions but basically yes, they can be used to help find people.

Perhaps I need to visit some kind of a club? That sounds like it might be the ideal setting to meet people like this. How could I find out more about Japanese language or culture clubs in my area? Though I do think that these days the internet provides a good opportunity to meet people on a more one-on-one basis. I'm not opposed to using either route.

Yes, you can hire a private investigator.
If you are not their family, you may need to shop around for PIs that will take your case, and you may need to prove that you are not stalking the person.
I have used PI before, and depending on the amount of information you have, it generally will cost 1M yen+