Rin Tohsaka is a female mage and a member of the Tohsaka Family. She's the daughter of Tokiomi Tohsaka, a master during the Fourth Holy Grail War, and became the master of Archer during the Fifth Holy Grail War. After the war she joined the Mages Association, and later left it, along with Waver Velvet, to dismantle the Holy Grail. In Fate/stay night and Heaven's Feel she plays a supporting character role, but is the main female during Unlimited Blade Works, and serves as the love interst for the main character, Shirou Emiya.
Rin arrives in Fuyuki with Luvia, but their fighting causes their Kaleidostick's to reject them and cancel their contracts. Ruby ends up in the hands of Ilya, and due to the Kaleidostick taking a liking to her, Rin forces her to act as her "servant" and collect the cards in her place.