I think he's probably Chinese American, 2nd generation. Chinese in-laws can be very difficult to get along with, one of my best friends who is Irish, great guy and nearly a perfect father, married a Chinese American and had some issues with his in-laws. He's managed to iron things out eventually but it can definitely be a source of marital instability.
I think Japanese people have a complex of superiority vs Koreans and Chinese, so that might have also been a small factor.
I think Japanese people have a complex of superiority vs Koreans and Chinese, so that might have also been a small factor.