Kirk here with an update on who in Kagoshima needs to evacuate. In short, it would seem that Level 5 (calling for all persons to evacuate) only applies to people on the island of Sakurajima, not to Kagoshima City or other nearby areas. The purple you see in the image indicates Level 5. I’m sharing a screenshot of the Japanese page because on the English page (see following image), the colors of the warning symbols are obscured by the overly large English text. What’s more, zooming doesn’t help; the English text is configured to display on top of the symbols at all zoom levels. An additional problem, is that it’s not exactly easy to switch to Japanese to see how that looks; there’s not toggle or link to the original Japanese. This is another example of the assumption that anyone who might begin by looking at an English-language page couldn’t possibly have any use for the Japanese-language page.
https://www.jma.go.jp/bosai/#lang=en&pattern=earthquake_volcano&area_type=class20s&area_code=4620100