Kirk here with a share from Kumamoto Japan Tourism about Okoshiki Kaigan – arguably Kumamoto’s best spot to photograph a beautiful sunset.
The post recommends days to get a good view. Ideally, low tide should come at about sunset. That’s what reveals that beautiful pattern you see in the photo. But, of course, there are other factors to consider – the weather, your own schedule, etc. So, you might want to look up the tide times yourself and decide weather or not to go. You can do that here:
https://tide.chowari.jp/43/432113/20456/
In 2016, a friend of mine who is an outstanding photographer came and we went to Okoshiki Beach to see and photograph the sunset. As I recall, the conditions weren’t ideal but the tide was fairly low when the sun set so we got some good shots. You can see a post about that day here.