Otoko's the daughter of the owner of Copenhagen, a bar in Fuyuki. She and Taiga Fujimura go way back—they were close friends in high school and stayed that way. During the Fourth Holy Grail War, Rider made off with a barrel of wine from their place that was supposed to go to the Fujimura family, which got Taiga motivated enough to track down whoever was responsible.
About five years before the Fifth Holy Grail War started, Shirou Emiya came to work for them. The guy was reliable to a fault—he'd take on literally any job they threw at him, even covering shifts when both Otoko and her father were laid up sick.
Content compiled by AnimeList.moe from publicly available sources.
