Because people, believe it or not, Google/search information about others, information that can't quite be determined on other social media platforms, it's suggested that you provide as much information about who you are trying to find here.
Be as descriptive as possible down to using their correct names written in kanji, if applicable.
The more information that you give, the higher likelihood that this page would rank high enough for someone to find when doing a minimalistic background check on themselves or someone else.
With that said, keep privacy in mind too. This information will be public; everyone will see it. Therefore, you should give as much as you can, but not too much as to go beyond what you would feel comfortable with the entire world knowing.
If that person is in Okinawa, wouldn't it be best to go to the govt. office and ask about the family register? It's really strange because my daughter really doesn't exist here in Japan because my wife never put her on the family register or whatever they call it. So its unlikely she can find out anything about the wife and me here.