Etymology and distribution of 古岡.

Furuoka 【古岡】^{レベル4
About 1,400}  The Japanese surnames etymology dictionary.

Oosaka-fu Oosaka-shi Plain Ward, Toyama-ken Toyama-shi .

① Korea type . Added "river" to the declaration. There is a record of naturalization on Gunma-ken Kiryuu-shi on February 24, 1968. The real name is a prefecture. 宣 Sen reference.

② Korean type . 宜川 's variant. There is a record of naturalization on July 4, 1969 at Toyama-ken Toyama-shi (Ogawano cho Kamikinagawa gun). Last name is surplus. 余 Yo reference.