Shirou Emiya, sole survivor of the Fuyuki City fire a decade prior, owes his life to Kiritsugu Emiya. Kiritsugu saved him by embedding the sheath Avalon within his body, then adopted him and instilled the philosophy of becoming a "Hero of Justice." This ideal, rooted in Shirou's survivor's guilt and distorted self-worth, manifests as a self-sacrificial drive to save others above himself. Kiritsugu provided incomplete and dangerous basic magecraft training. Shirou specializes in structural analysis and projection magic, possessing an elemental affinity for "sword." While his magic circuits are average, his unique origin and alignment enable exceptional skill in tracing and projecting bladed weapons, a talent honed through repairing objects. As Master of Saber in the Fifth Holy Grail War, Shirou's focus shifts to protecting his adoptive sister, Sakura Matou, after Saber is consumed by a shadow. Effectively eliminated as a Master, he continues fighting. He discovers Sakura is Rider's true Master, infected with Crest Worms by her grandfather Zouken Matou. The worms drain her mana, causing physical and psychological torment. Faced with saving everyone or prioritizing Sakura, Shirou abandons his hero ideal to protect her, promising never to betray her. This strains his relationship with Rin Tohsaka, Sakura's biological sister, though they later ally with Illyasviel von Einzbern after losing their Servants. Archer saves Shirou's life by severing his own arm, which is transplanted onto Shirou. The arm remains sealed with holy cloth due to the risk of Archer's power overwhelming him. As Shirou adjusts to the arm and grows closer to Rin, Sakura's jealousy intensifies, culminating in a romantic confirmation of their feelings. Sakura's connection to the shadow deepens; she unknowingly kills people while sleepwalking. After Gilgamesh attacks her, the shadow consumes him. Illya reveals Sakura is the Holy Grail's vessel. Zouken confirms the shadow originates from her and suggests killing her is the only solution, but Shirou refuses. Sakura returns to the Matou estate to protect Shirou, where her brother Shinji attempts to assault her. In panic, Sakura kills Shinji, triggering her full transformation into Dark Sakura as the shadow merges with her body. This marks the culmination of Shirou's choice to protect her at all costs. Shirou's journey through the Heaven's Feel narrative illustrates his progression from rigid idealism to a personal commitment centered on Sakura. His background as an orphan with survivor guilt and Kiritsugu's influence remain foundational, even as he abandons Kiritsugu's ideal. The physical toll of receiving Archer's arm and the emotional toll of witnessing Sakura's transformation define his role.