Etymology and distribution of 曽澤.

Sozawa 【曽澤】^{レベル1
Very rare}  The Japanese surnames etymology dictionary.

Kyouto-fu Kyouto-shi Nakagyo-ku. There is 勅使河原 surname. In Kyouto-fu there is a belief that it is from marrying the daughter of the imperial court. Unknown times. 勅使河原 Teshigawara reference.