Maybe I can help. I have a Korean girlfriend, but she used to buy her bras from the Japanese stores, becuase she couldn't fit into the Korean sizes.
She is 65cm (25.5inch) under and 94cm (37inch) or so over. Her bras are 65G. In US terms, this makes her about a 30E-F. In Australia, where we are, she is something like a 10E, which is virtually unobtainable.
Hope this helps.