Etymology and distribution of 古佐井.

Kosai 【古佐井】^{レベル1
Very rare}  The Japanese surnames etymology dictionary.

Shiga-ken , Oosaka-fu , Kyouto-fu .

① Shiga-ken Rittou-shi Originated from Rinnouchi in Oshara 's small character. It was in the Edo era near the same place.

② Topography . From within the village. Nagasaki-ken Gotou-shi Distributed in Uesakiyama-cho.

③ Topography . "Inside" was added to the village which is the surname of the Kamoshima-ken Amami archipelago. Estimated at the time of returning to Japan in 1953. 里 Sato reference.