Rin Tohsaka hails from an alternate reality where her family remained uninvolved in the Holy Grail War and unaware of the Einzberns, though her sister Sakura Matou was still adopted by the Matous. Witnessing Shirou Emiya's persistent attempts at a physically impossible high jump drew her to him, leading her to express affection more openly than other counterparts. Recognized for her magical potential, she joined the Mage's Association immediately after middle school, becoming Kischur Zelretch Schweinorg's direct apprentice. Zelretch tasked Rin and her rival, Luvia Edelfelt, with retrieving Class Cards causing dimensional instability in Fuyuki, equipping Rin with the sentient Kaleidostick Magical Ruby. Their initial mission failed due to intense rivalry, prompting Ruby to break its contract with Rin and bond with Illyasviel von Einzbern. Forced to supervise Illya as Ruby's new master, Rin guided her through collecting the Class Cards, a partnership starting contentiously. After securing all seven cards, Zelretch ordered Rin and Luvia to remain in Japan for a year to study "common sense," resulting in Rin working as a maid at Luvia's mansion due to financial constraints. During "2wei Herz!," Rin investigated anomalies tied to an eighth Class Card hidden at the earth pulse's core, revealed as Archer-class Gilgamesh. She coordinated Illya, Miyu Edelfelt, and Caren Hortensia to confront him, using hypnotic barriers to contain damage. When Gilgamesh absorbed Miyu, exposing her origins as a parallel-world Holy Grail, Rin supported Illya's transformation into Kaleido Liner Zwei to rescue her. Following Miyu's abduction by the Ainsworths, Rin and Luvia pursued her into a parallel world, where they were captured, brainwashed, and transformed into Ainsworth servants. Under Angelica Ainsworth's control, Rin fought Illya using a Nameless Class Card. Freed by Gilgamesh and Bazett Fraga McRemitz, she rejoined Illya's group. In this world, Rin encountered an alternate Sakura Matou attempting to kill Shirou Emiya. Rin intervened, distracting Sakura with Gandr curses while invoking their sisterly bond and expressing relief they could coexist as siblings in some reality. She later assisted in healing the injured Shirou using her pendant and witnessed Sakura's redemption via Rule Breaker. Rin's personality merges resourcefulness, competitiveness, and a tsundere nature. Her rivalry with Luvia frequently escalates into destructive confrontations, underpinned by underlying mutual respect. Financial pressures sometimes force her to compromise her pride for lucrative work. She harbors profound guilt over Sakura's adoption, channeling it into protective instincts and reacting intensely to alternate Sakura's suffering. As a mentor, she balances strictness with concern for Illya's well-being, though her magical guidance is often pragmatic and exposition-focused. Her abilities center on jewel magecraft, storing mana in gems for high-impact attacks, and firing the Gandr curse from her finger. She utilizes Thor's Hammer, an eight-step amplification ritual involving her Azoth Sword and German incantations, to empower allies' beam attacks. While competent in hand-to-hand combat and reinforcement magic, her healing skills are self-admittedly subpar, demanding significant time for stabilization before treatment.