Oonami 【大波】4 The Japanese surnames etymology dictionary.
Saitama-ken · Chiba-ken · Ibaraki-ken . Thing . Chiba-ken Asahi-shi From Nakedani's Oze River (Oyokawa) pharmacist. I tell him that the family of Mr. Kusunoki who came from the southern part of Wakayama-ken · Mie-ken (formerly Kii) who protected the Tanikawa Yakushi was called Meiji Shin surname at Toukyou-to Bunkyou-ku Hakusan. 楠木 reference. There is an example of pronouncing Oikawa as Oyokawa at Chiba-ken . 及川 reference.