He was just testing the extent to which they'll go under the brainwashing. I'm guessing if she'd been willing to take off her clothes he next would have likely asked her to harm herself. he needed to know how much control he had
I mean... the genocide, the murders, the attempted self-explosion... but you draw the line THERE?! Why is being a yandere somehow more important than the genocidal psycho that wiped out almost all of humanity smh
long story short: yes. its because Japan once invaded korea and committed a bunch of horrible atrocities, so generally speaking the koreans hate the Japanese... but that doesnt mean they hate manga and sushi and stuff so you get this weird dynamic. also korea has a massive inferiority complex...