Etymology and distribution of 歐.

Ou 【歐】^{レベル1
Very rare}  The Japanese surnames etymology dictionary.

Hyougo-ken Koube-shi Nada-ku. Hyougo-ken Nishinomiya-shi It was in Edo period as Naoko. I tell him that the descendants of the ronin of the Yamanaka surname who came from Gifu - ken Oogaki - shi renamed. 山中 Yamanaka reference.