This is an older scenery that doesn’t have a thread of its own; however it’s today become available on Orbx and appears to have just had an update (to v1.1.0), so an appropriate time to highlight it.
I reviewed their much newer Hiroshima recently and found it very good, apart from some low-res ground textures. Finding a changelog for Kumamoto is no easy task, but what leads me to suspect it’s just been updated is a totally new set of images compared to the original release on Simmarket (which also now features the revised set).