You "dated" her for two and a half years and "could have" married her....yet you know absolutely nothing about her other than her name. Sounds like you were just banging her and as soon as your assignment in Japan was up just turned your back and walked off without the slightest pretense of continuing the relationship or even keeping in touch. You blame being at sea, but I know for a fact the mail operated between Japan and any ship in the fleet. I was in the Navy homeported in Yokosuka in the '80s, dating a Japanese girl, and away at sea half the time too. It sometimes took weeks for them to reach me, but I still have the letters she wrote to me. For that matter, I still have the girl.
The very strong impression one gets from you is that she was just a local piece of tail you treated like a doorknob (turn it, tap it, and put it behind you). I am not moved to exert any effort facilitating your hooking up again.
Maybe you could ask some of your relatives who met her if they remember anything about her. Maybe they talked to her.....