Mikaela Hyakuya, originally named Mikaela Shindo, was born May 1, 2004, to parents devoted to the Hyakuya Sect. Following their deaths, he joined the Hyakuya Orphanage. As the eldest child, he naturally took charge of the other orphans, forging a bond with Yuichiro Hyakuya despite Yuichiro's initial resistance. Mikaela shone with kindness, cheerfulness, and protectiveness, always putting his adopted family first. He maintained hope and responsibility, organizing activities like ice cream trips and planning their escape from the vampire-dominated city of Sanguinem. Physically, Mikaela possessed wavy blond hair and blue eyes, giving him a distinctly foreign look in Japan. As an eight-year-old human, he dressed casually in jean shorts, a white hoodie, and a collared shirt. At twelve, living as human livestock in Sanguinem, he wore the standard uniform of capri shorts and a hooded shirt, depicted barefoot in the manga but wearing shoes in the anime. After Third Progenitor Krul Tepes turned him into an incomplete vampire, he developed fangs and pointed ears, often concealed by his hair. His eyes stayed blue until consuming human blood triggered a transformation to a complete vampire, turning them red. By sixteen, his hair reached his shoulders, and he donned elaborate vampire military attire: a white cloak, black-collared shirt, decorated jackets, thigh-high boots, and a sword at his hip, with the uniform design evolving to become more streamlined over time. As a demon, his appearance featured pointed horns, a wisp-like tail, and a sleeveless parka with fur trim, his eyes reverting to blue. Trauma profoundly altered Mikaela's personality. The human child was upbeat, empathetic, and resilient, using his charisma to inspire hope among the orphans. He displayed cunning and self-sacrifice, trading his blood to Seventh Progenitor Ferid Bathory for escape resources like a map and gun. Witnessing his family's massacre during the failed escape and his forced transformation into a vampire forged a cold, self-loathing, reclusive nature. He despised vampires for their cruelty and humans for their experiments, like those on Yuichiro. He isolated himself, interacting minimally except with Krul and Ferid, and resisted drinking human blood for four agonizing years to cling to his fading humanity. His sole motivation became rescuing Yuichiro, his last surviving family. After becoming a complete vampire by drinking Yuichiro's blood, emotional numbness deepened, though protectiveness remained. As a demon, he regained access to human-like emotions and memories, showing heightened protectiveness and introspection about his failures and desire for peace. Key events defined his path. Early orphanage camaraderie ended with the apocalyptic virus and vampire uprising, leading to subjugation in Sanguinem. The escape attempt at twelve resulted in the other orphans' deaths, his near-fatal injury, and transformation. Serving as a vampire soldier under Ferid and Krul for four years took him globally, witnessing human experimentation that deepened his mistrust of humanity. He reunited with Yuichiro during the Shinjuku invasion but failed to extract him. Severely weakened in the Nagoya battle, he consumed Yuichiro's blood to survive, becoming a complete vampire. He later aided Yuichiro's squad, struggling to trust them. Sacrificing himself to save Yuichiro triggered his transformation into a demon, regaining lost memories and confronting guilt in a dream-like "samsara" world where he relived idealized orphanage moments. This state also awakened his latent seraph gene, linking him to an ancient angelic lineage. Mikaela's relationships centered on fierce loyalty and conflict. His bond with Yuichiro was foundational; he saw Yuichiro as family and his reason for living, constantly risking himself for Yuichiro's safety. He distrusted humans broadly due to experimentation but gradually tolerated Yuichiro's squad, especially after fighting alongside them. With vampires, interactions were fraught: he loathed Ferid for murdering his family, maintained a complex alliance with Krul (who saved and manipulated him), and ignored or antagonized others like Lacus Welt. Internally, he wrestled with profound guilt over his family's deaths, self-hatred for his vampirism, and a recurring longing for peace. Mikaela developed unique traits and abilities. As a vampire, he wielded superhuman strength, speed, agility, and potent regeneration, healing fatal wounds and excelling in high-speed combat. His sword, powered by blood, unleashed destructive ranged attacks. He carried the seraph gene, a genetic link to an ancient angelic being tied to the "Michaela" trait, making him a target for factions seeking this power. This gene connected him to biblical symbolism, with Mikaela representing the archangel Michael against Yuichiro's Lucifer-like parallels. As a demon, he could manifest a dream world reflecting his deepest desires and feed on human emotions, though this left him vulnerable to external corruption.