Okinawa return trip

Is there a way to locate old local friends on okinawa that I've lost contact with? Like a phone book? Or can someone help me ? Returning mid next year after nearly 20 years and looking forward to seeing them if I can. I've already searched all the local social media but I'm having no luck.
Thanks

There is indeed a phone book for every district in Japan, but hardly anyone has been registering in the past decades. I'm sure it's a lot easier to just directly visit places where there may be people who know your friends.

Or if they were former classmates, you can visit your old school to present your ID so that the school could check the alumni. Similarly, there may be places where you can visit directly to show your ID to obtain info, as opposed to contacting from overseas where you cannot present your ID directly.

Also, you say you've been searching social media, but I wonder if you've searched Google or any other search engine. I've found several people through Googling, especially those who have blogs and those who are successful in certain organizations. And not everybody has a social media account.

As a side note, I once searched a childhood friend all over the Internet, visited the country she may be in, couldn't find her, came back home, and then I happened to do something that I'd never done before, which was to go into the social media again but this time simply searched "(her name) (the name of the city we grew up in)" and there she was. I think it's a bit unfortunate that people, mostly women, abandon their former family name upon marriage. It makes it very difficult to track them down.

Thank you for the reply. My problem is I was military and they were all okinawan citizens. When I left okinawa I wasn't on social media and neither were they. How often do they change cell phone numbers? I can see if I have my old cell phone from 20 years ago, their number may be on there. If not, any other suggestions? I've been to their houses before but I'm sure I won't remember as it's been 20 years and they lived with parents, we were all in early 20s