[5][6][7] Influenced by her father, Shinashi started training Judo at the age of 15, stopping the discipline after graduating from Nippon Sport Science University at 22.
[12] With the win she earned the opportunity compete for the inaugural DEEP Women's Lightweight Championship in a rematch against Hisae Watanabe.
[c][16] She capture the title by first defeating Fukuko Hamada via unanimous decision and then submitting Sachiko Yamamoto in the first round of the final.
[6] With more than three years removed from her previous bout, Shinashi faced Reina Kobayashi at DEEP: 112 Impact on February 11, 2023.
[22] Shinashi faced Kyoka Minagawa on November 11, 2023 at DEEP: 113 Impact, winning the bout via unanimous decision.