Etymology and distribution of オコイン.

Okoin* 【オコイン】^{レベル1
Very rare}  The Japanese surnames etymology dictionary.

Kanagawa-ken , Chiba-ken . 筧 variant of. Okayama-ken Okayama-shi Kita Ward Marunouchi was the Okayama samurai of the clan office, Ishikawa-ken Kanazawa-shi Marunouchi was in the Edo period in the Kaga clan in the Clan office. 筧 Kakei reference.