Mitoizumi Masayuki (born 2 September 1962 as Masato Koizumi) is a former sumo wrestler from Mito, Ibaraki, Japan. His professional career spanned 22 years, from 1978 until 2000. The highest rank he reached was sekiwake. He won over 800 career bouts and took the yūshō or championship in the top makuuchi division in 1992. Mitoizumi was nicknamed the "Salt Shaker", due to his habit of throwing enormous quantities of purifying salt onto the ring (dohyō) during the pre-match preliminaries. He is now a coach, and is known as Nishikido Oyakata.