Sunday Silence (1986-2002) is a successful American racehorse and winner of two of the American Triple Crown in 1989. The horse, however, is better known as the leading sire in Japan for 13 years, including 5 years posthumously. Many of his numerous offspring and descendants became successful racehorses themselves and several became popular sires and broodmares in their own right, especially Deep Impact (2002 - 2019), one of his most successful offspring and successor as a long-streaking leading sire (11 years and counting). His influence is so pervasive to the point that nowadays, almost all racehorses in Japan racing at any given level and aren't foreign-bred are direct descendants of Sunday Silence.
In the context of Umamusume, he is the RL sire or ancestor of a significant portion of the horse girls, especially the youngest in RL. Whenever he is portrayed as a horse girl, he usually takes the form of a look-alike of Manhattan Cafe (or being just portrayed by Manhattan Cafe) due to the original horse being said to be the spitting image of his sire, to the point of being able to stand-in as Sunday Silence in a TV movie about him and his Japanese owner, Yoshida Zenya.
