Nakayasu 【中安】5 The Japanese surnames etymology dictionary.
Fukuoka-ken , Hiroshima-ken Kure-shi . Terrain . From Hara and Oka. Fukuoka-ken Chikujou-gun Kouge-machi It is based in Seiyu branch. In the same place, tell Ooita-ken Nakatsu-shi Nenodori was a doctor of the lord of Nakatsu of the clan government. It was in the Edo period to the same clan.