In this continuity, Rin Tohsaka diverges significantly from her main universe counterpart. Her family had no involvement in the Holy Grail War ritual and no knowledge of the Einzberns, though her sister Sakura was still adopted by the Matous. She grew captivated by Shirou Emiya after witnessing his persistent attempts at an impossible high jump, openly displaying her affection rather than concealing it. Admitted to the Mage's Association directly after middle school, she became an apprentice under Kischur Zelretch Schweinorg, who tasked her to retrieve Class Cards using the Kaleidostick Magical Ruby alongside her rival Luvia Edelfelt.

Her appearance retains long black hair in twin tails tied by black ribbons, blue eyes, and predominantly red-and-black casual outfits, including a red long-sleeved shirt paired with a black miniskirt and thigh-high stockings. Her magical girl form features a red-and-white dress, cloak, and animal ears.

Personality-wise, she remains perceptive, competitive, and serious, with amplified tsundere traits concerning Shirou. Her fierce rivalry with Luvia often escalates into destructive confrontations, causing professional setbacks and comedic mishaps that undermine Illya and Miyu's view of her competence. Financial constraints force her to reluctantly accept high-paying jobs, suppressing her pride for income. She exhibits profound concern for Sakura, reacting with visible distress to revelations of Sakura's suffering in other worlds. She also displays heightened self-consciousness about her chest size, which Luvia frequently mocks.

Tasked by Zelretch with collecting Class Cards, Rin arrived in Fuyuki with Luvia. Their constant fighting caused their Kaleidosticks, Ruby and Sapphire, to abandon them. Ruby contracted Illyasviel von Einzbern instead, leading Rin to coerce Illya into acting as her proxy for card collection. After gathering the initial seven cards, Zelretch ordered Rin and Luvia to remain in Japan for a year to learn "common sense," resulting in Rin working as a maid in Luvia's mansion.

The discovery of an eighth Class Card prompted an alliance with Bazett Fraga McRemitz. Confronting the Archer-class Gilgamesh, Rin assisted Illya and Miyu in defeating him using the multi-step Thor's Hammer ritual, channeling amplified energy through their attacks. Following this victory, Gilgamesh transported the group to a parallel world where the Ainsworth family captured Rin and Luvia. Brainwashed into serving the Ainsworths, they fought Illya until freed by Gilgamesh and Bazett. Rin later aided an alternate universe Shirou Emiya after he was severely injured, healing him using a recovered pendant.

During the final battle against the Ainsworths, Rin intervened to protect Shirou from an alternate Sakura Matou, who denied their sisterhood due to her Rin's death. Rin expressed relief that they could have lived as siblings in that world. After Sakura's defeat, Rin speculated about Sakura's motives regarding Shirou and witnessed her redemption using Rule Breaker. She observed the aftermath as Emiya Archer confronted Darius.

Her magical capabilities include firing the Gandr curse from her finger, healing magic (though she admits weakness here), and complex rituals like Thor's Hammer, which uses eight jewels to create an amplification circuit. She retains proficiency in hand-to-hand combat and occasionally employs witchcraft techniques such as the Shared-Pain curse to torment Luvia. While competent, her effectiveness is often hampered by conflicts with Luvia.