Miku is a now retired former DEEP Women's Lightweight (106 lbs) champion which she held until her retirement. She has fought in promotions such as Valkyrie, DEEP, Shooto, Smackgirl and HEAT She holds notable wins over Hisae Watanabe, Carina Damm, Seo Hee Ham, Misaki Takimoto, Lisa Ellis, and Tomomi Sunaba. She also avenged every single one of her losses. She was known as one of the busiest fighters of all time, having squeezed 27 fights into a 5 year period. 

Matsumoto's road to MMA was interesting in that she was more into piano and penmanship than sports and she had no previous martial arts or combat sport experience. She only took up MMA as a part time job to kill time and save money after studying overseas.  

 
Miku was victorious in her MMA debut winning a decision. In her second fight she would face who would become her biggest rival in Misaki Takimoto. Takimoto would get the better of Miku, submitting her with an armbar. Miku would then win 7 straight fights and take on Takimoto again. Once again Takimoto would emerge victorious by submission. She would win her next two fights and then take on Carina Damm. Miku would lose by submission but the bout was clouded with controversy. When Damm was looking to secure an armbar  Miku yelled that Damm was grabbing her glove. However, the referee did not acknowledge the alleged foul and Damm then extended the armbar, prompting the referee stoppage despite Matsumoto's protests. One month later they would have a rematch, this time Miku would win a dominating decision. 

 
Next Miku would take on an up and coming American in Lisa Ellis. Ellis would win in an upset with a rare scarfhold submission. After the fight she returned to the DEEP promotion where she began to hit her stride with 2 submission wins, one over hot Korean prospect and future JEWELS champion Seo Hee Ham. This set up the 3rd fight between Miku and Takimoto. This fight had a different outcome than their previous two fights with Miku winning by armbar. This set her up for a shot at the DEEP Women's Lightweight (106 lbs) Title against champion Hisae Watanabe. Miku would earn the decision and the title after a very competitive battle. Most surprising was that she not only out grappled Hisae, but she also outstruck the dangerous kickboxer. 

 
She would win three non title fights, all three by submission, this set up her first title defense against Takimoto in their 4th and final bout. Miku showed just how far her game had come along by finishing Takimoto via body kicks. She would win 2 more fights before taking on Lisa Ellis in a rematch for the title. Two weeks before the fight she was involved in a cycling accident in which she injured her left hip flexors, reducing her to just light swimming for her final fight preparations. Miku would still go on to dominate the fight and would submit her by armbar in the 3rd round, she would later say that this was the fight that left the biggest impression on her. 

 
Miku fought her last fight against Tomomi "Windy" Sunaba. Miku won by decision and then disappeared for a few months, sparking rumors of a retirement. On February 28, 2010 at DEEP 46th Impact, Miku took to the ring. This time it was not as a participant, to the shock of the crowd Matsumoto announced her retirement at only 28 years old. Matsumoto stated that she had become detached from MMA and no longer had the ability to continue serious training or perform as a professional fighter. She further stated that she had no regrets about her decision to retire and does not plan to remain involved with MMA training or coaching in the near future. At the time of her retirement, Matsumoto was the #3-ranked pound for pound female MMA fighter in the world and the #2-ranked female flyweight. 

 
On April 17, 2010 Miku participated in a 5 minute retirement exhibition against close friend Megumi Fujii at DEEP 47th Impact. Miku finished the exhibition with a flying armbar. After the match a retirement ceremony was held for her with many of her peers paying tribute to her.