So yeah, this is Wu Zetian from Fate/Grand Order. AKA, the Assassin of Nightless City. She's one of the four newest servants released not too long ago for the Agartha chapter. I really like her design, and her official art is drawn by the dude that does art for Disgaea. She's based off the Chinese empress of the same name, so naturally she acts like a haughty ruler.