Fate/Zasshuu! (Shirou x Female Gilgamesh)

Shirou Emiya and Gilgamesh were fighting and Gilgamesh almost won....until a Heroic Spirit named Tiresias casted a curse on Gilgamesh turning him into a female, and Transporting Both Shirou and Gilgamesh to another world. To get out of this mess the Heroic spirit layed down one requirement...."Fall in love and make a...