[4] Oiwa made her senior international debut at the 2017 Minsk World Challenge Cup and finished fourteenth in the all-around.

[5] She then competed at the 2018 Asian Games in Jakarta where the Japanese team placed fourth behind Kazakhstan, Uzbekistan, and South Korea.

[6] Then at the World Championships in Sofia, she finished eighth in the team competition alongside Sumire Kita and Kaho Minagawa.

[12] At the 2019 World Championships in Baku, she finished nineteenth in the all-around final and eighth in the team competition with Sumire Kita and Kaho Minagawa.

[19] At the 2020 Olympic Games in Tokyo, Oiwa finished nineteenth in the qualification round for the individual all-around with a total score of 87.550.