Mizuno joined the senior national team in 2017. In March, she competed at the Rhythmic Challenge in Indianapolis, Indiana, winning gold in ball and bronze in all-around. At the end of March, she was assigned to three international competitions: Marbella Grand Prix in Marbella, Spain from March 31-April 2; Sofia International Tournament in Sofia, Bulgaria in May; and Guadalajara World Challenge Cup in Guadalajara, Spain from June 2-4. At the US Gymnastics Championships in June, she won clubs silver behind Olympian Laura Zeng. Mizuno competed at the Pan American Championships in October, capturing silver in hoop, ball, ribbon and all-around, behind teammate Evita Griskenas.