However, in the school in Taiwan, Ara Kinue was also recognized as "exotic" because she was originally from the part of Ryukyu Islands and Okinawa prefecture. Ara also became the target of discrimination and bullying at the primary school in Keelung because of her Okinawan background. 

Japanese at that time did not really understand Okinawa prefecture. Okinawans were called "Ryukyuans", and became a target of discrimination. I know one Okinawan guy, who received the tertiary education and eventually became the principal of the middle school in Taiwan. Because the Okinawan label could be the obstacle of the social rise, he changed his registered address from Okinawa to Tokyo.
Okinawa used to be the Ryukyu Kingdom, right? Okinawa's culture and language were different from the Japanese mainland, and Japanese did not give respect to the differences. 

Indeed, it was not uncommon for Okinawan immigrants in colonial Taiwan to experience discrimination and take insults from other Japanese immigrants. To avoid such unfair treatments, some Okinawan immigrants covered their identities or changed their registered addresses to another prefecture.