TV-Series
Description
Mikaela Hyakuya first lived as a human orphan after being abused by his parents and then abandoned. He was taken in by the Hyakuya Orphanage, where he acted as the protective older brother figure to the other children, including Yuichiro Hyakuya. After a global virus wiped out all humans over the age of thirteen, the orphans were abducted by vampires and taken to the underground city of Sanguinem. Within this environment, Mikaela revealed a cunning and strategic nature. He voluntarily allowed the vampire noble Ferid Bathory to drink his blood in exchange for better food and, more importantly, to secretly obtain a map that would allow his family to escape. This plan ended in tragedy when the escape attempt failed and his orphanage family was murdered by Ferid Bathory. Mortally wounded, Mikaela was forcibly turned into a vampire by the Third Progenitor Krul Tepes against his will, an act that defined the rest of his existence.

Despite the harsh circumstances of his childhood, Mikaela maintained a kind-hearted and upbeat personality while he was human, largely because of the family he found at the orphanage. As a vampire, this core kindness remains but is overshadowed by a deep internal conflict. He despises his own vampiric existence and is tormented by a constant and growing lust for blood, which he views as monstrous. This struggle to preserve his humanity is a defining trait; for as long as possible, he refuses to drink human blood, even at the cost of severe physical weakness. His personality is also marked by a deep-seated selflessness and unwavering loyalty, particularly toward Yuichiro. He is distrustful of both humans and vampires, viewing both sides as corrupt, and he believes the Japanese Imperial Demon Army is merely using Yuichiro as a tool.

Mikaela's primary motivation is the protection of Yuichiro, whom he considers his only true family and the most important person in the world. His single-minded devotion drives nearly all of his actions. He seeks to rescue Yuichiro from what he sees as exploitation by the human army and to find a way for them to be together, free from the conflicts between humans and vampires.

In the Battle in Nagoya arc, Mikaela's role is that of a search for Yuichiro. He spends the campaign desperately trying to reach his childhood friend, operating from within the vampire faction under the authority of Krul Tepes. He is not a primary fighter on the side of the humans but rather a conflicted figure whose loyalties are torn. His arc culminates in his long-awaited reunion with Yuichiro. When Mikaela is mortally wounded during the conflict, he is forced to drink Yuichiro's blood. This act completes his transformation into a full vampire and allows him to finally satisfy his thirst, giving him a new, albeit painful, reason to continue living.

The most significant relationship in Mikaela's life is with Yuichiro Hyakuya. Their bond is profound and obsessive, grounded in their shared past at the orphanage and a mutual promise of family. Mikaela's devotion to Yuichiro is absolute and serves as both his greatest strength and his primary vulnerability. His relationship with Krul Tepes is complex and defined by reluctant dependence. She saved his life by turning him into a vampire, but he is also dependent on her blood to quench his thirst, making their alliance one of manipulation and necessity. His interactions with Ferid Bathory are antagonistic; Ferid is the one who murdered his family, and Mikaela continues to view him with deep hatred and distrust, though Ferid often mocks and manipulates him for his own amusement.

Mikaela undergoes significant development throughout the story, transitioning through three distinct biological states: human, vampire, and eventually demon. His character arc is a tragedy of survival and adaptation. As a human, he was a hopeful and cunning leader. As a vampire, he is a tormented figure fighting against his own nature. His experiences force him to confront what it means to stay human when his body has become monstrous. Through his reunion with Yuichiro and the acceptance of his vampiric needs, he finds a twisted form of purpose, moving from a state of despair to a grim determination to protect what he loves at any cost.

As a vampire, Mikaela possesses enhanced physical capabilities, including greatly increased strength, speed, and regenerative abilities. He can reattach severed limbs, and only a weapon containing a powerful demon can halt his regeneration. He wields a unique sword that, when commanded, drinks his blood and sprouts thorny vines. The more blood the sword consumes, the more powerful it becomes, turning the blade red and further increasing Mikaela's own strength and speed in proportion. His primary weakness is his dependency on blood. He is reliant on Krul Tepes's blood to stave off his thirst, but this supply becomes increasingly ineffective. When starved, he risks losing control and attacking those around him. Both Krul and Ferid warn that prolonged starvation will cause him to degenerate into a demon.