[3][4][5] Koyomi Matsushima is currently training under Japanese MMA Legend Satoru Kitaoka and has been a combat sports fan all his life, growing up watching karate, judo, wrestling, and mixed martial arts bouts in his native Japan.
[6] On May 2, 2015, early in his mixed martial arts career, Matsushima faced future Lethwei world champion Dave Leduc at Hybrid Pro Series 3 in Gatineau, Canada, and won by first-round TKO in 19 seconds.
[14] Matsushima was scheduled to face former ADCC and IBJJF champion Garry Tonon in a featherweight title eliminator at ONE Championship: Big Bang on December 4, 2020.
[21] In his first bout since the loss on Road To UFC, Matsushima faced Ryuji Takashio at DEEP 114 Impact on July 2, 2023, knocking him out with a soccer kick in the first round.
[22] Matsushima faced Karshyga Dautbek on January 21, 2024 at Top Brights 1, losing the bout via TKO stoppage at the end of the first round.