Ryosuke Mizumachi is a former Japanese professional basketball player who played for the Akita Northern Happinets of the B.League in Japan.

The Akita Northern Happinets are a Japanese professional basketball team based in Akita that competes in the Eastern Conference of the First Division of the B.League. The team was formed as an expansion team of the bj league in 2010 and found success for the first time in 2013–14, finishing their fourth season as league runners-up. They went on to finish as runners-up for the second year in a row in 2014–15 and in third place in 2015–16, the final season of the bj league.