hmm... I cant really tell how looks like the relationships between parents and their kids in japan. In Europe... when kids are gettin older and older they starting to get their own opinions, they are about to start makin first serious decisions but regarding love I've always doing what I want! The opinion of my mother or father wasn't crucial.
There never was a situation like this that my mother dont agree about some girls. But tell... what about this that guy is Vietnamese? They are on lowers social status in Japan or what?
You know if you really love that guy I suggest this. Try to oppose your mom. Do it in hard way! Maybe when she recognize that you really care about this guy, that it really is love (BTW you are convinced that this IS REAL LOVE??) she would surrender! But it is just hypothetical. Try to consider every way and possibilities and do your best
!