[4][5] She was unsuccessful in her first attempt to win a world title, losing via split decision to South Korea's Hong Su-yun in a contest for the vacant WBO female light-flyweight crown at KBS Hall, Kyoto, Japan, on 14 May 2017.
[8][9] Ozawa bounced back to win the vacant Japanese flyweight title on 14 April 2019, beating Hye Soo Park by unanimous decision at KBS Hall.
[10][5] After a three-year hiatus during which time she gave birth to a son, Ozawa returned to the ring on 30 May 2022, to challenge WBO female super-flyweight World champion Miyo Yoshida at Korakuen Hall, Tokyo, Japan.
In a written statement revealing her decision she said: "With the support of my husband (pianist Ryohei Kishimoto) and the patience of my son, I was somehow able to take part in the world fight in May.
I have been working hard to become world champion, so I am grateful to have been given this opportunity, and I feel that I have received a great reward at the end.