You have to understand that there was no such concept as racism in asia, it was homogeneous society ( more so in Japan/Korea, less in China and the rest but majority of the people are from mongoloid race ), we didn't invade other country land and bring anyone in for slave ( only our people ), so yes, lots of people are less aware of racism concept. People can just make joke, or say things like that without any worry.
I'm not saying it is a good thing being ignorance, but you just need to see the context here. Asian culture background are totally opposite from the west. I mean it gets to the point where you can tell them it is racist and they might not even understand what does that mean. Hence racism joke, ads , etc all over the place not just japan but most of other asian countries.