Zōken Matō, born Makiri Zolgen, led the 500-year-old Zolgen mage lineage from Kyiv until exile forced their relocation to Japan as the Matou clan. A co-architect of the Holy Grail War with the Einzbern and Tohsaka families, he devised the Master-Servant system and the Heaven’s Feel ritual to access the "Root" and achieve a world without suffering. His reverence for Justeaze Lizrich von Einzbern, who became the Grail’s core, spurred him to prolong his life through grotesque methods, awaiting the ritual’s fruition. Centuries of decay eroded his idealism, replacing it with a fixation on immortality through moral transgressions. To preserve the Matou magecraft, Zōken adopted Sakura Tohsaka after her father abandoned her for her sister Rin. He infused her body with Crest Worms—parasites reshaping her biology and mind to host Angra Mainyu, the Grail’s tainted spirit. One worm forcibly claimed her virginity, epitomizing his ruthless exploitation of kinship. He similarly deceived his grandson Kariya during the Fourth Holy Grail War, implanting Crest Worms under the guise of liberating Sakura, all while ensuring Kariya’s inevitable demise. In the Fifth War, Zōken lurked in secrecy until Rider’s defeat and Shinji’s ineptitude compelled him to summon True Assassin from Hassan-i Sabbah’s remnants. He usurped Lancer’s contract by mortally wounding Bazett Fraga McRemitz and exploited Sakura’s link to Angra Mainyu’s Shadow. As her psyche fractured, he implanted a final Crest Worm near her heart to seize control once the Grail awakened. Sakura defied him, assimilating Assassin via the Shadow and crushing Zōken’s worm form, erasing his corporeal existence. His last surviving worm crawled toward the Greater Grail during the final clash, only to encounter Illyasviel von Einzbern clad in the Dress of Heaven—a mirror of Justeaze. The vision reignited a vestige of his past aspirations, allowing him to relinquish his grip on life. His death dissolved centuries of scheming, fracturing the Matou lineage and emancipating Sakura. Zōken’s trajectory traces the corrosion of altruism into nihilism. Once determined to eliminate human anguish, he devolved into a manipulative architect of suffering, weaponizing familial bonds, psychological torment, and bodily violation to prolong his influence. His machinations across successive Grail Wars crystallized tragedies, most profoundly Sakura’s metamorphosis from a tormented heir into an avatar of annihilation.