[1] He trained at Houston Gymnastics Academy with Kevin Mazeika while attending Alief Taylor High School.

In his first year of college competition in 2009, Mizoguchi competed in the parallel bars, pommel horse, floor exercise, and in the all-around.

He finished in sixth place on the floor exercise at the Big Ten individual event finals with a score of 14.725.

[4] Throughout the 2010–2011 season he gained a career-high seven individual titles while helping the University of Illinois gymnastics team along with other athletes such as Daniel Ribeiro, Justin Spring and Yoshi Mori.

In his junior season, he helped the University of Illinois win the Big Ten Championships for a third straight time.