Etymology and distribution of 磐上.

The Japanese surnames etymology dictionary.
https://play.google.com/store/apps/details?id=info.jigensha.jcedfreeGoogle Play で手に入れよう https://apps.apple.com/us/app/id1471109324
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Ratio of 磐上.

カンマ区切りで複数の名字を指定できます。

Etymology of 磐上

Distribution of 磐上
Ranking
1 Saitama-ken(0.000881%)
2 Yamanashi-ken(0.000844%)
3 Gunma-ken(0.000405%)
4 Shizuoka-ken(0.000111%)
5 Chiba-ken(Very rare)
6 Toukyou-to(Very rare)