Kasumi is an accomplished gymnast living alongside her sister Sumire Yoshizawa and the sisters' father Shinichi Yoshizawa. They also lived alongside their mother and grandmother. She and Sumire had been practicing rhythmic gymnastics since childhood under Coach Hiraguchi who trained them with a spartan degree, although Kasumi had a much more natural and shorter learning curve compared to her younger sister. She also calls those she respects as "senpai".