Yuki Sakurai, later Yuki Giou, has ash-bronze hair and golden eyes, frequently noted for a handsome yet feminine appearance causing occasional mistaken identity. Abandoned as an infant and raised at Asahi Orphanage, he harbors deep-seated fears of abandonment and feelings of being unwanted, fostering a strong desire to be needed while disliking being a burden. His innate empathic ability lets him perceive others' emotions and memories through physical touch, causing significant childhood suffering but forging a resilient and unyielding nature. As bearer of the "Light of God" (Kami no Hikari), he wields mystical abilities: a protective yellow Halo Wall requiring substantial mental energy, often causing collapse after extended use; Empathic Healing that transfers others' wounds and pain to himself, frequently causing prolonged unconsciousness or life-threatening exhaustion and guilt in those healed; Barrier Sensitivity to detect and dismantle mystical barriers; and later, Sword Summoning, manifesting a blade from a past incarnation to free trapped spirits. Yuki is part of a reincarnation cycle, having previously lived as Yuzuki—a woman confined to solitude, tormented by nightmares, and romantically involved with Luka Crosszeria. His male reincarnation is viewed as a potential end to the cyclical conflict or a desire to forget. Yuki retains no conscious past-life memories but experiences nostalgia around Luka and specific locations. Relationships define his journey: Luka Crosszeria, whose bond spans lifetimes, protects Yuki since infancy; Yuki feels drawn but insecure, wondering if Luka's devotion is tied to his past self, unaware Luka conceals their romantic history believing Yuki wished to forget. He gradually earns loyalty from initially distant Zweilt Guardians like Hotsuma Renjou, who resented his past incarnation, and Kuroto Hourai, who saw him as "pampered," through selflessness, saving Shuusei Usui and Tsukumo Murasame to gain their lifelong pledges. Takashiro Giou is viewed as an elder brother despite orchestrating his orphanage placement, their relationship a mix of manipulation and care. Reiga Giou, formerly his cherished orphanage mentor Kanata Wakamiya, causes emotional turmoil through betrayal and eventual protection. Yuki's development involves confronting truths: learning his birth caused his mother's death during a ritual, processing repeated deceptions by allies, and reconciling his current identity with past lives. He evolves from an insecure youth seeking purpose to a resolved figure embracing his protective role, stating: "If I cannot erase sadness and hate, I at least want to protect those who gave me a reason to live."