In 2015 she took the JRA Award for Best Three-Year-Old Filly after winning both the Yushun Himba and the Shuka Sho as well as finishing second in the Daily Hai Queen Cup and the Rose Stakes.

As a five-year-old she won the Hanshin Himba Stakes and finished third in both the Takarazuka Kinen and the Queen Elizabeth II Cup before being retired from racing at the end of the year.

[3] She was from the fifth crop of foals sired by Deep Impact, who was the Japanese Horse of the Year in 2005 and 2006, winning races including the Tokyo Yushun, Tenno Sho, Arima Kinen and Japan Cup.

[5] On 7 December 2014 Mikki Queen began her racing career by finishing a close second to Gilda in an event for hitherto unraced juveniles over 1400 metres at Hanshin Racecourse.

After racing towards the rear of the field, Mikki Queen produced a strong run in the straight, gained the advantage 50 metres from the finish and won by three-quarters of a length from Rouge Buck.

On 18 October the filly started 2/1 favourite for the 20th edition of the Shuka Sho over 2000 metres at Kyoto Racecourse when her seventeen opponents included Touching Speech, Let's Go Donki, Tosen Victory, Queens Ring, Kokorono Ai and Cat Coin.

Starting from a draw on the far outside she raced in eighth place before making rapid progress on the inside in the straight and after taking the lead 100 metres out she held off the late challenge of Queens Ring to win by a neck.

"[8] On her final race of the year Mikki Queen was matched against older horses and started third favourite for the Japan Cup over 2400 metres at Tokyo on 29 November.

[10] In the official Japanese rankings Mikki Queen was rated equal with Let's Go Donki as the best three-year-old filly, nine pounds behind the top colt Duramente.

[11] On her four-year-old debut Mikki Queen started favourite for the Grade 2 Hanshin Himba Stakes over 1600 metres in April but failed by a neck to catch the front-running six-year-old mare Smart Layer.