Tsuetate Onsen, in northern Kumamoto, is famous for it’s display of thousands of koinobori wind socks. The display was cancelled last year because of COVID-19 (I guess the koinobori don’t fly well when masked ;) ) but is back this year and will continue until May.
– Kirk
P.S. You can find a Japanese TV (RKK) report here:
https://rkk.jp/news/backno_page.php?id=NS003202103261605480111