I found an interesting article about a manga that depicts Okinawa as a "slave island." The manga is titled "Ryukyu Kingdom: The War of the Three Kingdoms" or "Ryukyu Kingdom: Sangoku no Tachi" in Japanese.
: Due to its graphic depiction of sexual violence and "Guro" elements, it is frequently cited in discussions regarding the boundaries of extreme fetish media. It is not considered a mainstream title and is intended strictly for niche, adult audiences who specifically seek out dark fantasy or horror erotica. Legal Availability & Links
The best way to support the artist and view the work is through the official Kicktraq listing or specialized adult manga retailers that partnered with the Kickstarter project.