My current lass is a 4 or 5 (36C for Canadian size) which is pretty large for a girl from Sapporo, but she's considering to get implants (yay me!) so she may be getting up to a full-on 5 or possibly even touching on 6. Anything larger than that (and that's natural) would sag too quickly. I don't want to have to lift anything up before I go down.