[2] At the 2013 Japan Junior International, Miyakawa finished twelfth in the all-around, fifth on vault, and won a bronze on floor exercise.

[9] She won a bronze medal in the vault final behind Wang Yan of China and Ellie Downie of Great Britain.

[11] Miyakawa ended her junior career at the Élite Gym Massilia where she finished seventh with her team and twenty-eighth in the all-around.

[15][16] At the Japanese Individual Event Championships, Miyakawa won the gold medal on vault with a 14.925 average and finished fifth on floor exercise.

[17] She was then named to the Japanese team for the 2015 World Championships along with Natsumi Sasada, Aiko Sugihara, Asuka Teramoto, Yuki Uchiyama, and Sakura Yumoto.

[23] Miyakawa began the 2016 season at the International Gymnix where she won the silver medal on vault behind Shallon Olsen and placed sixth with her team, seventh on uneven bars, and eighteenth in the all-around.

[27] She was then named to represent Japan at the 2016 Summer Olympics alongside Asuka Teramoto, Mai Murakami, Aiko Sugihara, and Yuki Uchiyama, and they placed fourth in the team final behind the United States, Russia, and China.

[30] She was then selected to compete at the World Championships alongside Asuka Teramoto, Mai Murakami, and Aiko Sugihara.

[35][36] The Japanese Gymnastics Federation found that Hayami had repeatedly employed violence towards Miyakawa during training including slapping her face and dragging her body from September 2013 until May 2018.

[44] At the All-Japan Event Championships, she won the bronze medal on the floor exercise behind Aiko Sugihara and Chiaki Hatakeda.