Uma Musume: Cinderella Gray (TV)

The series' plot is based on the career of racehorse Oguri Cap (1985-2010), who won 22 out of 32 races from 1987 to 1990, as well as the 1991 Japanese Horse of the Year award. Oguri Cap's diamond-pattern headband is designed after the racing silk worn by the jockeys that raced with the racehorse.

Jō Kitahara is based on three people: Koichi Oguri (the original owner of the real Oguri Cap), Katsumi Ando (Oguri Cap's jockey in Kasamatsu), and Masao Sugi (Oguri Cap's trainer in Kasamatsu). Kitahara not being licensed to train at a national level is based on Koichi Oguri not having a Japan Racing Association (JRA) owner's license and Ando failing his national license exam.

Belno Light is based on the racehorse Twin Bee (1985-date of death unknown), who spent her entire career in Kasamatsu and won 10 out of 45 races. She is also based on Masaru Minowa, a farrier who shoed the real Oguri Cap in Kasamatsu.

Fujimasa March is based on March Tosho (1985-date of death unknown), who beat the real Oguri Cap in two out of seven races in 1987 and 1988. March Tosho continued to compete mainly on dirt tracks in Kochi until 1992.

Dicta Striker is based on the racehorse Soccer Boy (1985-2011), who won six races in his 11-race career from 1987 to 1988. She is named after the French racehorse Dictus, Soccer Boy's sire (father). Her yellow and blue jacket is patterned after the racing silk worn by the jockeys that raced with the racehorse. Soccer Boy would sire successful racehorses such as Narita Top Road (1996-2005) and Hishi Miracle (foaled March 31, 1999).

Ginjirō Musaka is based on Isō Sahashi, who took over ownership of the real Oguri Cap from Koichi Oguri as part of the racehorse's transfer to the JRA nationals.

Akitsu Teio is based on the racehorse Nippo Teio (1983-2016), who never won a Classic race, but dominated the mile-length races and won the 1987 Tenno Sho (Autumn). None of his progeny were able to match his success, but his most famous one was Haru Urara (1996-2025), whose 0-113 career made her one of the most popular racehorses in Japanese history.

The real Maruzensky (1974-1997) would go on to sire numerous successful racehorses, with his progeny including Sakura Chiyono O (1985-2012), Rice Shower (1989-1995), Winning Ticket (1990-2023), Mejiro Bright (1994-2004), Special Week (1995-2018), Cesario (2002-2021), Buena Vista (foaled March 14, 2006), Curren Chan (foaled March 31, 2007), and Daring Tact (foaled April 15, 2017).

Tamamo Cross' racing costume uses the same blue and red colors and pattern of the racing silk worn by the jockeys that raced with the real racehorse (1984-2003), who won nine races in his 18-race career from 1987 to 1988 and won the 1988 Japanese Horse of the Year award.

In episode 1, Oguri Cap reveals she was born with weak legs, and her mother constantly massaged them to improve the blood circulation and allow her to walk. The real racehorse was foaled with a deformed right front hoof, and he had a frail body because his dam (mother) White Narubi (1974-2001) refused to nurse him. Because of this, ranch workers cared for Oguri Cap and corrected his leg until he grew up normally.

In episode 7, Oguri Cap is barred from entering the Classic races (Satsuki Sho, Japanese Derby, and Kikuka Sho) due to her failure to submit her registration form. This happened to the real racehorse in 1988 due to his regional career resulting in his owners submitting his registration late. Oguri Cap's wins led to protests by fans to have the JRA allow the racehorse to participate in the Classics. Eventually, the JRA revised the rules to allow late entries to run in the Classics in 1992, a year after Oguri Cap's retirement.

In episode 9, Maruzenky mentions that she was prohibited from participating in the URA Classics. This stems from the same JRA rules that prevented Oguri Cap from running the Classics. In the case of the real Maruzensky, he was treated as a mochikomi-ba (brought-in horse), as his American dam Shill was pregnant with him during her transfer to Japan. Mochikomi-ba were bound by restrictions on foreign-bred horses despite being born in Japan. The JRA eventually revised the rules in 2002 to allow foreign racehorses to participate in the Classics.

In real life, Sakura Chiyono O's win at the 1988 Tōkyō Yūshun (Japanese Derby), as depicted in episode 9, was seen by horse racing fans as Maruzensky's revenge after he was prohibited from competing in the JRA's Classic races due to the rules against foreign-bred racehorses.

In episode 9, a glimpse of T.M. Opera O is shown during the scene when the URA starts revising its rules on uma musume participating in the Classics. This is in reference to the real racehorse (1996-2018) being the first to benefit from the 1992 revisions when his owners failed to register him. T.M. Opera O was able to participate in the Classics after his owners paid an additional fee as per the new rules.