[5] In 2014, Kokumai won the gold medal in the women's kata event at the Pan American Sports Festival held in Tlaxcala, Mexico.

[7][8] At the 2017 World Games held in Wrocław, Poland, Kokumai lost her bronze medal match against Sandy Scordo of France in the women's kata event.

[9] In 2018, she competed in the women's individual kata event at the World Karate Championships held in Madrid, Spain where she was eliminated in her third match by Viviana Bottaro of Italy.

[15][16][17] At the 2020 Summer Olympics in Tokyo, Japan, Kokumai competed in the women's kata where she lost her bronze medal match against Viviana Bottaro of Italy.

[18] A few months after the Olympics, she also lost her bronze medal match against Bottaro in the women's individual kata event at the 2021 World Karate Championships held in Dubai, United Arab Emirates.