She won the 2010 Jewels -56 kg Rough Stone Grand Prix tournament at 16 years of age, becoming one of the youngest female champions in a major MMA promotion.
A year later, Inoue joined Hakushinkai Karate and also began training mixed martial arts (MMA).
[15][16] At this event, Inoue began using the ring name Mizuki instead of her real name, which she used in her previous amateur kickboxing bouts.
[18] Returning to professional competition, on September 20, 2010 (2010-09-20) at J-Girls Catch The Stone 10, Inoue defeated Anna Saito by unanimous decision after three rounds.
[32][33] She won the fight by referee stoppage in the third round to advance to the Shoot Boxing Girls S-Cup 53.5 tournament final.
[34][35] Inoue faced Ai Takahashi once again in the 2012 Shoot Boxing Girls S-Cup 53.5 tournament final on August 25, 2012 (2012-08-25).
She defeated Takahashi by unanimous decision after six rounds to become the first Shoot Boxing Girls S-Cup 53.5 champion.
[36][37] She defeated Izumi Noguchi, Miyo Yoshida and Ai Takahashi in one night to become the 2013 Shoot Boxing Girls S-Cup 53.5 champion.
[44][45] At just 16 years old, Inoue debuted in MMA at Jewels 10th Ring on October 10, 2010 (2010-10-10) during the 2010 Rough Stone Grand Prix -56 kg tournament, submitting the more mature Abe Ani Combat Club member Emi Murata with an armbar in the second round.
[46][47][48] On December 17, 2010 (2010-12-17) at Jewels 11th Ring, Inoue defeated the more experienced Asako Saioka via technical submission (referee stoppage, armbar) to win the 2010 Rough Stone GP -56 kg tournament.
[65][66] Inoue made her North American debut against Bec Hyatt at Invicta FC 6: Coenen vs. Cyborg on July 13, 2013 (2013-07-13).
[73][74] On February 16, 2014 (2014-02-16), Inoue faced Emi Tomimatsu to determine the inaugural Deep Jewels lightweight champion.
[76] Inoue was scheduled to face Milana Dudieva on March 24, 2018, at Invicta FC 28: Morandin vs. Jandiroba, however Morandin pulled out of the fight with Jandiroba, allowing Mizuki to step up into the main event which was for the vacant Invicta FC strawweight championship which she lost via split decision.
[77] Inoue was scheduled to face Heather Jo Clark on November 16, 2018, at Invicta FC 32: Spencer vs.
[89] After 3 years off due to injury, Inoue faced Hannah Goldy on September 23, 2023, at UFC Fight Night 228.