Kiritsugu Emiya appears in story flashbacks through Shirou Emiya's memories, specifically during his time as Shirou's adoptive father after the Fourth Holy Grail War. Residing together in Fuyuki City, Kiritsugu adopted a domestic role and taught Shirou foundational cooking skills, including hamburger steak—a dish that became a recurring meal in their household.

He developed a paternal relationship with Taiga Fujimura, Shirou's legal guardian. Kiritsugu welcomed Taiga's frequent visits, doting on her and solidifying her regular presence in their daily life. His interactions with both Shirou and Taiga displayed quiet care, contrasting with his earlier existence. Flashbacks depict moments of familial warmth, like them playing together in a sketch-like, abstract style evoking nostalgia and tenderness.

Though Kiritsugu's past as the "Magus Killer" and personal tragedies remain unexplored in this series, subtle connections surface through food. For instance, a brownie recipe by his deceased wife Irisviel von Einzbern resurfaces, prompting their daughter Illyasviel von Einzbern to recall childhood memories of foraging walnuts with Kiritsugu. These culinary traditions bridge his earlier family life with Shirou's experiences.

Kiritsugu's influence on Shirou is foundational: his cooking lessons directly inspired Shirou's passion for meal preparation, central to the series. This domestic mentorship established Shirou's identity as a caregiver through food. Kiritsugu's physical presence is confined to these flashbacks, as he died years before the main story events.