Sakura Matō, originally Sakura Tōsaka, is the biological younger sister of Rin Tōsaka, born to Tokiomi Tōsaka and Aoi Zenjō. Due to the Tōsaka family tradition allowing only one heir to inherit their magecraft, she entered adoption by the allied Matō family one year before the Fourth Holy Grail War. This adoption aimed to make her their magical successor, as their biological heir, Shinji Matō, lacked aptitude. Her transition subjected her to extensive physical and psychological conditioning under patriarch Zouken Matō, including the implantation of parasitic "Crest Worms." These worms drained her magical energy while amplifying carnal impulses, permanently altering her hair and eyes from black and aqua to violet. For eleven years, Sakura endured systematic abuse and sexual violence from Shinji, who resented her status as heir. Her adoptive uncle, Kariya Matō, attempted to rescue her by participating in the Fourth War but died; Sakura misinterpreted this death as a warning against defying Zouken, deepening her resignation. Her emotional resilience stemmed from witnessing Shirō Emiya's perseverance during a track event, inspiring her to join Homurahara Academy's archery club to be near him. After Shirō sustained an injury, she began regularly visiting him, assisting with household chores and developing a profound, unspoken affection. In the Fifth Holy Grail War, Sakura was the true Master of Rider but relinquished control to Shinji under duress. Her latent affinity for the rare element "Imaginary Numbers," tied to dimensional voids, allowed her to manifest a corrosive shadow during sleep. This shadow absorbed Servants and humans to fuel Angra Mainyu (All the World's Evils), an entity bound to her via Grail fragments implanted by Zouken, establishing her role as the "Black Grail" counterpart to the Einzbern vessel. The *Heaven's Feel* route details Sakura's psychological fragmentation. Shirō's growing closeness to Rin intensified her suppressed envy and trauma, accelerating her corruption. After Shinji attempted to rape her and threatened exposure, she inadvertently killed him, triggering her full transformation into "Dark Sakura." Her hair turned white and eyes red, granting conscious control of the shadow. Consumed by Angra Mainyu's influence, she abducted Illyasviel von Einzbern to complete the Grail, absorbed Servants including Gilgamesh and Berserker, and ravaged Fuyuki City. Shirō's intervention halted her descent. Rin confronted her but could not strike the final blow, leading Shirō to sever Sakura's link to Angra Mainyu using "Rule Breaker." War overseer Kirei Kotomine attempted to manipulate the Grail's emergence but was defeated by Shirō. Illyasviel sacrificed herself to destroy the Grail and preserve Shirō's soul. Freed from the Matō curse with Zouken excised, Sakura reconciled with Rin and continued living with Shirō, the now-incarnated Rider, and their friends. Her arc concluded symbolically as she viewed cherry blossoms, reflecting her name and rebirth. Beyond *Heaven's Feel*, Sakura appears in *Fate/hollow ataraxia* as a more confident figure leading the archery club and managing the Matō household, though retaining lingering jealousy toward Rin and others close to Shirō. Spin-offs like *Fate/kaleid liner Prisma Illya* depict alternate timelines where she is a victim of the Ainsworth family or wields the Gilgamesh class card before being killed by Shinji.