From Japanese 東 (higashi, “east”), from the way the eastern or right side of the sumo ranking list is considered more prestigious, by analogy with the rising sun as opposed to the setting sun.
"higashi." YourDictionary, n.d. Web. 17 August 2018. <http://www.yourdictionary.com/higashi>.
higashi. (n.d.). Retrieved August 17th, 2018, from http://www.yourdictionary.com/higashi