I don't know for sure but if you're talking about the White you just posted here
http://www.quiltingboard.com/vintage...n-t252393.html
I would suspect that machine uses class 15 bobbins.
Rodney
EDIT: I should have added that from what I've seen the Japanese Whites were basically the same as other Singer 15 clones, just badged differently. I don't know anything about the more modern ones.