Blue horse

... Horses are most distinctive because of their coat color, and white horses in particular were considered sacred and offered in religious rites, and were also used by nobles. A bluish white horse was called an "aoma," and the term "ao" was used to refer to horses in general, even blue-black horses. Yellow-brown horses were called "kawarake," and the Kanazawa domain disliked keeping them, as they were believed to bring about strange happenings.

*Some of the terminology that refers to "Aouma" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…　また馬は毛色がもっとも特徴となるので注意がはらわれ，ことに白馬は神聖なものとして神祭に供せられ，また貴人の乗用ともなった。青みがかった白馬は〈あおうま〉といわれ，馬一般の呼称にもあおの名が用いられ，青黒色のものまで同じ呼称となった。黄褐色の馬は〈かわらけ〉といって金沢藩はこれを飼うと怪異があるとしてきらった。…

※「あおうま」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報