Kitai 【北井】5 The Japanese surnames etymology dictionary.
Yamanashi-ken Hokuto-shi . Good neighbor . Yamanashi-ken Hokuto-shi Originated from the vicinity of Mukogawa flowing through the middle of Akeno-machi. In the same place, Spring Princess of Takeda Shigeru's younger sister (with a woman with the eleventh woman), who was based in Yamanashi-ken as a warring country era, became leprosy and tells that she retired with eight followers. The place name was also called "Kaizukawa". 武田 reference.