While there's no mention of Japan, it's a common theme with these "trolls"/posters to usually admire Japan as shown in the image of the character with the Japanese flag pin. The far rights in the case of S. Korea and Japan funny enough is in an "okay" term (more like a master and a slave relationship I'd say)as seen from the current president's extremely pro Japanese stance. Often on south Korean internet, users nicknamed the president governor-general Yoon which was the title given to the head of the Korea when it was still a colony of Japan,

She's a character from a Korean gacha game. Pretty sure the incel is just using her as a surrogate face because he wants to fuck her