Here’s an article about a site of historical importance that is located in northern Kumamoto.
“The Mitsui Miike Coal Mine, one of several UNESCO registered Meiji Industrial Revolution Sites since 2015. While the central role of the coal industry in Japan’s industrialisation was stressed through the world heritage registration process, the close relationship between pre-war industrialisation and development of the modern penal system, and the use of prison labor, has been less acknowledged. In Miike, use of convict laborers from the nearby Miike shūjikan (central correctional institution) was indispensable for the operation of the coal mine during the early Meiji period.”
The article also discusses the use of labor from Yoron, now part of Kagoshima. I have seen a documentary that includes testimony that the treatment of people from Yoron was worse than that of the convicts because the people from Yoron were not considered to be Japanese. I think the depth of discrimination against people from Okinawa is an important clue to understanding how Okinawa came to be the site of U.S. bases. (Of course, it’s complicated and its not only about Okinawans not being seen as fully Japanese . . . )
– Kirk