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 and followed the racehorse to the JRA nationals.

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) was undefeated in his eight-race career from 1976 to 1977. He 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. She speaks in Kansai dialect as an homage to Michio Mino, the real racehorse's owner, being from the Hanshin region.

Lord Royal is based on the racehorse Legend Teio (1983-date of death unknown), who won five races in his 22-race career from 1986 to 1989.

Long Live Free is based on the racehorse Running Free (1983-date of death unknown), who won seven races in his 47-race career from 1985 to 1991.

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 missing the deadline of submitting his registration to the JRA. Oguri Cap's winning streak in the lower divisions 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.

In episode 11, Sirius Symboli does a twirling dance that injures two competitors on her way to the starting gate. This is a reference to the 1988 Mainichi Okan, when the real racehorse (1982-2012) kicked Legend Teio and Dyna Actress, forcing Legend Teio to withdraw from the race due to the injuries he sustained. Sirius Symboli was reportedly agitated and stressed from having to compete in Europe alone after Symboli Rudolf fell ill before both horses began their tour. Upon his return to Japan, he was no longer the competitive racehorse he was.

Tamamo Cross' backstory in episode 12 is based on the true-life history of the real racehorse. Nishikino Farm, the owner of Tamamo Cross, faced severe financial problems that he attempted to give Tamamo Cross and his dam Green Chateau (1974-1987) to a nearby farm in the Inaba region which housed Oguri Cap, but the farm rejected the offer due to the time being a breeding season. The two horses were eventually sold to Michio Mino of Tamamo Co. Ltd.