Leonardo da Vinci manifests as a Caster-class Servant aligned with the Chaldea Security Organization. Historically recorded as a peerless male genius of the 15th–16th century, this incarnation adopted the form of the Mona Lisa, embodying the ideal beauty pursued during life—a choice reflecting a belief in evolving cultural standards, including the potential normalization of desiring a "beautiful girl" form. Summoned as Chaldea’s third Heroic Spirit during the FATE system's incomplete stages, initial instability nearly caused departure. Interest in Chaldea’s mission and persuasion by Romani Archaman secured permanent residence, sustained within a duplicate puppet body echoing a certain doll maker’s techniques. Serving as Special Honorary Technical Advisor, Da Vinci supports Rayshift operations through technical expertise and mission planning, including securing leylines for base camps. Personality balances sharp rationality with relentless curiosity. Calm and observant, Da Vinci accurately assesses personal and others' capabilities, maintaining composure even in dire situations. The unexpected sparks intense fascination rather than distress. Though inhabiting a young female form, gender awareness remains minimal, exhibited by unrestrained nudity post-bath regardless of company. Self-identified as a "pervert," this trait remains unconcealed. After contracting with Ritsuka Fujimaru, interactions shift toward a "teacher close in age" dynamic rather than authoritative mentorship. Genius extends beyond conventional fields into magecraft. Despite negligible innate Magic Circuits and no familial Magic Crest, mastery of multiple thaumaturgical attributes and systems was achieved rapidly. When questioned by Clock Tower magi, Da Vinci attributed this to omnipotence—a title embraced after recognition as the "Universal Man" (Uomo Universale). This self-awareness of boundless capability enabled magical prowess alongside scientific and artistic achievements. Key relationships include Romani Archaman as a close colleague, with dialogues occasionally referencing obscured criticisms. Sherlock Holmes evokes irritation yet underlying respect. Historical rival Michelangelo is acknowledged as one of few equals in fine arts, privately considered a dear friend despite their competitive legacy. A truncated interaction with Makiri Zolgen (Matou Zouken) notes early acquaintance and recognition as an excellent magus. Following death during Chaldea’s assault by the Foreign God, a backup "Rider"-class vessel designated "Gran Cavallo"—named after an unfinished horse statue—activates. This younger form, colloquially "Da Vinci-chan" or "Da Vinci Lily," inherits memories but self-identifies as distinct from the original. Spirit Origin output is deliberately reduced for efficiency, resulting in diminished combat capability and reliance on equipment like roller skates, missile-launching backpacks, and deployable "Ultimo Manipulator" arms for energy projection or physical strikes. Personality in this Rider form retains core curiosity but adopts gentler, more youthful speech patterns. Interactions reflect student-like eagerness to learn rather than instruct. Insecurities surface regarding comparisons to the original’s accomplishments, fueling a drive to create new legacy-worthy memories. Relationships adjust: admiration for the original Caster mixes with competitive aspiration; Holmes’ secretive nature causes frustration; summer activities with Ritsuka Fujimaru and Mash Kyrielight emphasize lighthearted camaraderie; Goredolf Musik evokes paternal analogies. Notable contributions encompass piloting the Shadow Border during Chaldea’s escape, technical modifications like enhancing Billy the Kid’s firearm, and participation across multiple Lostbelts. In Avalon le Fae, separation leads to undercover work in Salisbury’s taverns gathering intelligence. Later captivity in Mictlan necessitates rescue during sacrificial rites. Abilities as Caster include the Noble Phantasm "Uomo Universale," an AoE Arts attack ignoring defense with critical rate reduction. Skills encompass "Inherent Wisdom" (self-Guts, defense, and NP damage buffs), "Mona Lisa" (debuff immunity, HP/NP regeneration, party Arts boost), and "Pioneer of the Stars" (NP charge, ignore invincibility, critical star generation). Passives "Territory Creation" and "Item Construction" enhance Arts performance and debuff success rate. As Rider, class skills include "Riding B" and diminished "Territory Creation C," while the unique "Overhaul E" offers limited party restoration via pseudo-spiritron nanomachines.