Sakura Matou, born Sakura Tohsaka, is the biological sister of Rin Tohsaka, the biological daughter of both Tokiomi Tohsaka and Aoi Tohsaka. When she was young her father gave her to the Matou Family to be groomed as it's next leader, completely unaware of the suffering that she was undergoing during that time.
She appears in Fate/Zero as a minor character, and in Fate/Stay Night and Unlimited Blade Works as a minor character, and Heaven's Feel as a major character, becoming not only the master of Saber, but also the love interest of the main character, Shirou Emiya.