Just a few days after release, Umamusume: Pretty Derby is going viral— inspiring livestreams, memes and TikTok edits—the bizarre anime girl racing game is proving immensely popular online.

First released in 2021 as a mobile game for iOS and Android, Umamusume is a racing simulator and a gacha game, featuring anime “Horse Girls” with horse ears and tails, sprinting around a racing track.

Umamusume’s Horse Girls aren’t the equine enthusiasts of our world, but animal-human hybrids. Sort of.

In the world of Umamusume, Horse Girls are reincarnated racehorses from Earth, birthed in human form, but gifted with superhuman speed and stamina. For whatever reason, all are female—even famous stallions are reborn as cute anime girls.

For those interested in delving deeper into the lore, the game also has a multiple-season anime adaptation that, from the clips posted online, actually looks fairly thrilling.

One user review on Steam succinctly summarized the strange world of Umamusume, writing: “The most terrifying thing about the Umamusume universe is that real horses don't actually exist.”

After launching on Steam on June 24, Umamusume suddenly exploded in popularity, introducing gamers to the ins and outs of horse racing—cute anime girls, it seems, are the key to success, in any field.