Hiraoka 【平岡】6 The Japanese surnames etymology dictionary.
Hokkaidou , Miyagi-ken Watari-gun Watari-chou , Toukyou-to . Miyagi - ken Watari - gun Watari - chou , Miyagi - ken Sendai - shi Aoba Ward Kawauchi was in the Edo era in the Sendai Samurai of the Clan office. The same samurai is said to have called "Maiyan" from Mai Yu in Fukushima-ken Date District. Period, location unknown. It is unknown if Maiyuu exists.