An Assassin-class Servant in Fate/Grand Order.
Historically known as the lover of Xiang Yu. She has a very long brown-black hair, wears a black dress and wields two swords. In her unascended form she braids her hair and wears a pair of glasses, but takes them off and puts her hair down after first Ascension.
Yu is an immortal hermit, which by Type-Moon lore is considered a species of natural spirit and a vampire similar to True Ancestors like Arcueid Brunestud.
Since she's been ostracized by humans for millennia for being a vampire, she greatly hates mankind. She also deeply despises Koyanskaya because she witnessed Daji, another incarnation of the Great Fox, bring down an empire.
As her unascended form indicates, she is the true identity of Akuta Hinako.