I finally got to get an idea about what the pop singer GWINKO was all about when JTM introduced me to her material a couple of years ago. Through her 1990 "Yokubari na Weekend"（よくばりなウィークエンド）, I got the impression of the Okinawan singer as a dynamic singer of poppy R&B.
But she can also sing some straight dynamic pop according to her "Mermaid in Summer" from her final album to date, "Princess Moon" from 1994. Some very summery synths populating this track as people enjoy a fine time at the beach. The music was provided by Masaya Ozeki（尾関昌也）and the lyrics are from Ikuru Kabuchi（橙育琉）, and it's pure speculation on the reading of that lyricist's name but I tried my jisho.org best.
Up to this point, I've only been able to judge from a couple of songs but with "Mermaid in Summer", there is some aspect of GWINKO's voice that reminded me of early 1980s Seiko Matsuda（松田聖子）for some reason.