Love Cosmetic conducted a survey nationwide to find out the bust size of women from the 47 prefectures of Japan. With 18 prefectures in the B-cup size and 17 in C-cup, the average woman seems to fall within these two sizes. Women in Hiroshima, Okayama, Osaka, Nara, Yamanashi, Niigata, Fukushima and Miyagi claim to be D-cups while those in Kyoto and Gifu boast of E-cup bust sizes. Saitama was the lone prefecture in the A-cup category.
Love Cosmetic didn't reveal numbers to their survey so can't really say how much truth there is in this. Anything about breasts and colour-coded maps are sure to be of interest though and this trended on Twitter a while under 'bust size, 'average bust', 'Saitama is the holy ground of small boobs' and 'Gifu and Kyoto are E-cups'.