On the 7th (Monday of last week), it seems that a sun halo was visible in Kumamoto and other parts of Kyushu. I didn’t see it but saw something about it on a news program I had recorded and wound up looking at today. A halo is “the name for a family of optical phenomena produced by light (typically from the Sun or Moon) interacting with ice crystals suspended in the atmosphere.” Even in the summer, I guess that very high (and thin) clouds can produce this kind of effect. – Kirk
https://en.wikipedia.org/wiki/Halo_(optical_phenomenon)
P.S. The photo is from the following page:
http://weathernews.jp/s/curation/detail.html?cuid=202106070055