Kirk here sharing an article about an island in the Amakusa area called Yushima (湯島, “Island of Hot Water”), also known as Dangojima (談合島, “Island on which Locals Conspired in the Shimabara Rebellion of 1637). According to the article, it has one more name: “cat island.”
https://japannews.yomiuri.co.jp/features/travel-spots/20221008-62999/
William has written about this place here: