Okubo 【尾久保】2 The Japanese surnames etymology dictionary.
Hiroshima-ken Kure-shi , Chiba-ken , Toukyou-to . Kai is an old pronunciation and means "Kai family (Kaike)". In the Shimane-ken west (formerly Iwami-kuni), I tell him that descendants of Mr. Kikuchi named "Kai family" as well. Unknown times. It is unknown whether Kai family exists. 甲斐 reference. 菊池 reference.