Sakura Matou, originally Sakura Tohsaka, is Rin Tohsaka's biological younger sister and the daughter of Tokiomi Tohsaka and Aoi Zenjou. Adhering to magus traditions limiting inheritance, Tokiomi gave her for adoption to the allied Matou family. Patriarch Zouken Matou sought to train her as heir since his grandson Shinji Matou lacked magic circuits, subjecting Sakura to years of physical and psychological torment. Zouken implanted parasitic Crest Worms into her body, altering her hair and eye color from black-brown and teal to violet. These worms drained her mana while amplifying her carnal impulses and sexual arousal. Resentful of her status, Shinji later initiated regular rape. This suffering rendered her emotionally withdrawn, fostering deep resentment toward Zouken, Tokiomi for abandoning her, and Rin for never rescuing her. The sole positive influence was adoptive uncle Kariya Matou, who died attempting to win the Fourth Holy Grail War to free her; Sakura misinterpreted his death as a warning against defying Zouken. Her life shifted upon witnessing Shirou Emiya persistently attempting a high jump during track practice. Inspired, she joined the archery club to observe him. Two years before the Fifth Holy Grail War, she approached Shirou after an injury, offering help with household chores. This became routine, and her frequent visits to the Emiya residence fostered a profound, possessive romantic attachment. Her personality contrasts sharply: around Shirou and Taiga Fujimura, she displays a gentle, cheerful demeanor, but appears silent and submissive elsewhere. She conceals significant knowledge, like Shirou's status as a magus, to maintain their relationship. Physically, she possesses a developed physique with large breasts, which she finds embarrassing. Her attire typically includes a pink ribbon gifted by Rin in childhood, her Homurahara Academy school uniform, and casual wear consisting of a pink cardigan, white top, and cream skirt. In the Heaven's Feel route, she emerges as central. She is the true Master of Rider, having transferred command to Shinji via a Command Spell due to reluctance to fight. Her rare "Imaginary Numbers" magic affinity enables shadow manipulation. Crucially, her body functions as a Lesser Grail (the "Black Grail") after Zouken implanted a fragment of the corrupted Holy Grail from the previous war. This connection manifests as "The Shadow," a voracious entity linked to Angra Mainyu (All the World's Evils) that emerges when she sleeps, consuming people to gather energy. The Crest Worms exacerbate her psychological instability, heightening jealousy toward women close to Shirou, particularly Rin and Saber. Her sense of taste deteriorates, affecting her cooking. After Shinji forcibly administers a mana-disrupting potion, she loses control, leading to a confrontation where Rin confirms their sisterhood. Shirou, learning of her Grail vessel role and abuse, abandons his ideal of becoming a "Hero of Justice" to protect her exclusively. Their physical relationship intensifies, partly driven by the Crest Worms' influence. The film *Heaven's Feel II. lost butterfly* depicts pivotal developments. During a nighttime episode, the Shadow consumes civilians and defeats Gilgamesh. Sakura regenerates after Gilgamesh wounds her by merging with the Shadow. Shirou discovers her connection but cannot kill her despite Zouken's urging. After Shinji attempts to rape her again at the Matou mansion, she accidentally kills him in self-defense. Horrified, she undergoes a forced transformation into "Dark Sakura" as the Shadow fully possesses her. This adaptation alters her corruption by emphasizing remorse over Shinji's death before the takeover. Visually, Dark Sakura has white hair, red eyes, a purple ribbon, and a black dress with red markings. Her character arc resolves diversely. In the visual novel's Heaven's Feel True End, Shirou destroys Angra Mainyu with Illya's help, freeing Sakura. She lives peacefully with Shirou and Rider, later becoming archery club captain. In the Normal End, Shirou sacrifices himself; Sakura waits decades for his return, maintaining the Emiya household until her death, envisioning him in the afterlife. In *Fate/hollow ataraxia*, she exhibits greater confidence as archery club captain and head of the Matou household, though she retains jealousy toward other women and occasionally displays dark traits as comedic relief. She also tends a cherry blossom tree symbolizing her growth. In spin-offs like *Fate/kaleid liner Prisma Illya 3rei!!* and *Oath Under Snow*, alternate versions include a mind-controlled doll and a participant in a parallel Grail War who spares Shirou but is killed by Shinji. She appears as a Lancer-class Servant possessed by the goddess Parvati in *Fate/Grand Order*.