Help with Japanese bra size?

Hi. I need to buy a bra- but I've noticed that the Japanese bra's seem to be sized differently, like A70, B70, A75, C80 etc.
My measurements are underbust-66cm and top bust-80cm.
Can anybody be able to tell me which sized bra i need to buy?
and what is the difference among A, B, C, D....??

The way bras are sized in Japan is "underbust size (in cm)" + "cup depth (in alphabet)." The cup depth is measured in terms of the difference between top and underbust in cm, and 10cm = A, 12.5 cm = B, 15cm = C, 17.5cm = D, etc.

So 66cm and 80cm would be C65 or possibly D65. If you find the underbust too tight, you could go for B70 or C70.

http://www.japan-guide.com/forum/quereadisplay.html?0+47400

Thank You AK.

http://store.la-beauty.net/other/30.html

There is size chart. Japan - US comverting.