Shinji Matou is the eldest son of Fuyuki City's declining Matou mage family. Generational thinning of the Matou bloodline left Shinji, the biological heir, born without functional magic circuits. This inadequacy defines him after Sakura Matou is adopted as the family's magical successor. Initially resistant to an outsider, Shinji eventually accepts Sakura but masks his feelings behind teasing due to his arrogant nature. His discovery of Sakura infested with Crest Worms in the Matou worm pit alters everything. Following this, his father Byakuya grows distant, and Shinji blames Sakura for destroying his dream of becoming heir, initiating systematic abuse. He mistakes her silent acceptance for submission. After Byakuya's death, Shinji escalates the abuse to include sexual violence, viewing Sakura as his property. Shinji maintains a complex middle-school friendship with Shirou Emiya. While deriding Shirou's selfless nature, Shinji values their companionship yet resents Shirou's growing closeness to Sakura. He is academically successful and serves as vice-captain of Homurahara Academy's archery club, where charisma and athleticism earn him popularity despite chauvinistic and narcissistic tendencies. His personality blends arrogance, entitlement, and an obsessive drive to prove his worth, particularly to his grandfather Zouken Matou. This compels him to participate in the Fifth Holy Grail War using Rider, a Servant originally summoned by Sakura. Shinji coerces control of Rider through Zouken's intervention, seeking validation as the rightful Matou heir and magical abilities. Within the *Heaven's Feel* route, specifically *lost butterfly*, Shinji's actions intensify. He kidnaps Sakura and uses a self-developed alchemical potion to forcibly activate her magical energy, triggering her connection to the Shadow. Confronted by Shirou and Sakura at Ryuudou Temple, Shinji's failure to control Rider exposes Sakura as the true Master, shattering his remaining self-worth. In desperate spite, he douses Sakura with the potion and flees. Later, at the Matou mansion, he attempts to rape Sakura again while blaming her for his magical incapacity. Threatening to reveal their abusive history to Shirou, he declares he would disclose "EVERY SINGLE TIME WE F***ED!!". This provokes Sakura into killing him via the Shadow's influence, catalyzing her transformation into Dark Sakura. Across other *Fate/stay night* routes, Shinji's role varies but consistently reflects his core traits. In the *Fate* route, he activates Rider's Blood Fort Andromeda at the school, endangering students to gain power, and is killed by Illyasviel von Einzbern after Rider's defeat. In *Unlimited Blade Works*, he receives Gilgamesh as a Servant from Kirei Kotomine after losing Rider and attempts to rape Rin Tohsaka before being fatally wounded. Spin-offs like *Fate/EXTRA* feature an alternate version—an eight-year-old gaming prodigy possessing similar arrogance but no direct Fuyuki Matou connection. This version participates in the Moon Holy Grail War with Rider (Medusa), treating the lethal conflict as a mere game. Shinji's background provides further context. He studied abroad during the Fourth Holy Grail War, unaware of his uncle Kariya Matou's involvement and death. Zouken executed his mother for failing to produce a magus heir, compounding family trauma. Though capable of dedication—evidenced by archery skills and creating over 600 potion variants—his magical incapacity and Zouken's manipulation warp his ambitions into destructive obsessions. Posthumous appearances in sequels like *Fate/hollow ataraxia* depict a less antagonistic yet still abrasive personality in scenarios allowing his survival.