Grandparents won't come to my wedding because we are inter-racial...

Honestly if the loved you they would support you no matter what your decision is and all you can do is ask. If they don't want to then you should still give them an invitation personally. Maybe if you try to explain your love for him them they would be less judgmental and accept the fact your a woman of your own.

Tell them they are too old to go anyway then. So take that.

Love is suppose to be unconditional for and older suppose wiser couple your grandparents.Need to be shown what that really means. When you do wedding pictures do some with an empty space where they could have been in it made sure you sent a note, missed you and this is where you should have been. Tell them you respect their decision and they should learn to respect yours. For there will be a time when greatgrand children come into the picture and you,yourself will like that phase of life. Wish you both the best,enjoy life to the fullest, it's too short not to get what you want out of it.

I'm also a Japanese myself and I'm married to a black man (which is sometime "worse" than just marring a "gaijin"). My grandpa is the same way. We've beem married for two years, and I think he's got used to the fact that I'm married to a black gaijin. Plus, my parents know my husband and they are telling him how much they love my husband. So it may be a tough time for you for now, but I bet you anything, as soon as they see their great-grand child, they will forget what they were upset about : )