so mostly the japanese people have their own server on wiimmfi and im guessing theyre not nice to casual players
The Japanese have their own region (not server as Wiimmfi is the only server connected to) on Wiimmfi, just like any other part of the world is set to be in a different region. Many Japanese people find Wiimmfi to be fascinating and so the Japanese region is pretty populated. datraptor implies that this region is the only real active region, and knowing generic Asian (/ Japanese) players, they're playing on a highly competitive level. This doesn't neccesary mean that theyŕe not nice to casual players, but they are just racing on a very high tier.
It is possible to change your region with region changers, so that eg. you can jump in the Japanese region. (Be aware that if you do this in practice you will have a very high ping / delay in matches.)