As a human child before the apocalypse, Mika appears as a young boy with short, wavy blond hair and striking blue eyes, giving him the appearance of a foreigner in Japan. His usual attire consists of casual clothing, including short jean shorts and a white hoodie over a collared shirt. Occasionally, he is also seen wearing an oversized jean jacket. Despite his youth, Mika is considered very handsome, even at this young age. His muscular build, even at the age of eight, foreshadows the physical strength he would later develop as a vampire.

At the age of twelve, Mika is living as livestock under the vampire’s control. He wears the standard livestock uniform, which consists of Capri shorts, a hooded shirt, and a collar with shoes. This attire signifies his status as a captured human being, with little autonomy. While the manga depiction differs, in the anime, Mika is shown wearing shoes with his uniform.

After Mika’s transformation into a vampire, his appearance changes significantly. As an incomplete vampire, his most noticeable change is the growth of fangs, although his eyes remain blue. When he drinks human blood, particularly Yu’s blood, his eyes turn red, signaling his transformation into a complete vampire. At the age of sixteen, Mika’s hair grows longer, reaching down to his shoulders.

Mika’s attire as a vampire is sophisticated and elegant, reflecting his noble status. He wears a white cloak with a hood that has four gold buttons on the slit in the front. The cloak ties at the chest with a sideways bow, and the bow’s long tails are secured with a gold insignia and a chain that connects to a gold circle. The cloak’s design is further enhanced by black padding on his left shoulder.

Underneath the cloak, Mika wears a white coat with notch lapels outlined in black, which extends down his shoulders and arms. The coat is adorned with eight gold buttons arranged in two vertical rows, with a black belt in between the fourth and third button, secured by a gold buckle. The coat’s design is accented by two thin, isosceles triangular openings in both the front and back. He wears a black collared shirt with a gold brooch in the center.

Mika completes his vampire ensemble with white gloves, thigh-high black boots with three small gold buttons at the bottom, and a sword carried at his left hip. The overall design of his clothing reflects his status as a powerful and distinguished vampire, emphasizing both formality and combat readiness.

As a child, Mika was selfless, friendly, and outgoing. He exhibited empathy and kindness, often trying to understand the feelings of others around him. When he first met Yu, Mika went out of his way to welcome him into the orphanage, responding to Yu’s anger with a calm and understanding attitude. Mika held his family, especially the other orphans, close to his heart, and he was willing to sacrifice for their well-being. His strong sense of familial responsibility was shown when he offered his own blood to a vampire to provide food for the group. Mika believed in the importance of thinking strategically for survival, as demonstrated when he stole a map and a gun to help the orphans escape the vampire city, even though it became clear the escape was a setup. Despite the danger, Mika’s love for his family drove him to run towards Ferid, sacrificing himself to give Yu a chance to escape.

Mika’s transformation into a vampire deeply conflicted him, as he was initially against it but had no choice. He struggled with the trauma of his past and the loss of his family, which remained a major source of inner turmoil. His vampirism was a constant concern for him, and he appeared troubled when Yu asked whether he was still human. Despite these internal struggles, Mika continued to be a resilient and selfless individual. Even after being transformed, he still prioritized protecting Yu and his loved ones above all else. He was physically resilient, as shown when he sustained a serious injury but continued to function without displaying much pain. Mika’s loyalty to his family remained unwavering, and he was willing to sacrifice his own happiness for their safety and well-being.

Mika’s bravery is one of his defining traits, as he often displayed a level of courage that surpassed fear of extreme danger. Whether facing lethal attacks or being surrounded by enemies, Mika never showed signs of backing down. Even when weakened and defenseless, he did not hesitate to stand against threats like the Four Horseman of John, showing his dedication to fighting for what mattered most to him.

When Mika fully transitioned into a complete vampire, his perspective shifted slightly. He expressed happiness, perhaps as a sign of accepting his new identity or finding a sense of peace after years of conflict. This change in his demeanor reflects his ability to adapt to the harsh realities of his new existence, but it also highlights his continued struggle between the desire for peace and the need to protect those he loves, especially Yu.

Despite his complex feelings about his transformation, Mika’s deep love for Yu and the bond they shared remained central to his character. His selflessness, bravery, and determination to protect those he cares about continued to drive his actions, regardless of the challenges and hardships he faced as a vampire.

Mikaela Hyakuya, or Mika as he is often called, was introduced to Yuichirō (Yu) when the latter arrived at the Hyakuya Orphanage. At that time, the director of the orphanage introduced Yu as the newest addition to their family. Mika was one of the first to approach Yu, bringing along Ako and another orphan. With a friendly and warm demeanor, Mika welcomed Yu to the orphanage, expressing empathy for his situation. He related to Yu on a personal level, as Mika himself had experienced the loneliness and pain of being an orphan. Although initially sad due to the traumatic circumstances surrounding his own past, Mika reassured Yu that he now had a family to call his own.

Mika’s kindness and understanding were evident as he reached out to Yu, offering his support and assuring him that, from that moment onward, things would improve. He encouraged Yu to join the family, emphasizing that he was no longer alone. Mika’s compassionate nature and his ability to empathize with Yu’s troubled experiences made him an important figure in Yu’s life, and his offer of comfort laid the foundation for a bond that would shape their futures. Mika’s kindness, despite his own hardships, reflected his deep sense of responsibility towards others, especially the family they had formed in the orphanage.

As a vampire turned by the third progenitor, Krul Tepes, Mikaela Hyakuya possesses formidable supernatural abilities that greatly enhance his strength and combat prowess.

Superhuman Strength and Speed
Mika’s vampirism grants him incredible physical strength and speed. His speed allows him to avoid powerful attacks, such as the detonation of spell tags, and his strength enables him to engage in fast and powerful combat techniques. Mika can move faster than most humans and even evade attacks from skilled opponents. His agility allows him to leap to great heights and quickly adapt to his surroundings.

Regeneration
Mika has enhanced regenerative abilities, allowing him to heal from wounds that would otherwise be fatal to a normal human. His vampiric nature ensures that even serious injuries can be recovered from quickly, making him a formidable adversary in battle.

Vampire Swordsman
Mika wields a unique sword that is specially designed for his vampiric abilities. Unlike other vampire swords, which are known for having spikes that pierce through the palm, Mika’s weapon is adorned with thorny red vines that emerge from two holes in the golden-colored pommel. These vines wrap around his hand, adding a distinct feature to his weapon. The silver blade is soaked in red, drawing upon blood to enhance Mika’s physical abilities. This connection to blood amplifies his power, enabling him to perform devastating attacks.

Ranged Destructive Attacks
Even when Mika’s sword is not empowered by his blood, it has the capability to emit destructive ranged attacks, allowing him to strike multiple targets at a distance. The sword’s blood-based abilities are versatile and highly effective in combat, making it a dangerous weapon for any opponent.

Mika’s natural abilities make him a powerful force in both close-quarters combat and ranged encounters, and his regenerative powers ensure that he can withstand tremendous damage, further amplifying his deadly effectiveness in battle.

Yūichirō Hyakuya
Mika’s bond with Yu is the cornerstone of his character. He considers Yu his only family and devotes himself to protecting him, even at great personal cost. Their relationship is central to the series’ emotional depth, highlighting themes of loyalty and sacrifice.

Krul Tepes
As the vampire queen who turned Mika, Krul has a complex relationship with him. While she uses Mika as part of her own plans, she also shows moments of genuine care, making their dynamic ambiguous.

Ferid Bathory
Mika harbors a deep hatred for Ferid, whose actions resulted in the death of his family and his forced transformation into a vampire. Their interactions are marked by tension and hostility.

Moon Demon Company
Mika’s encounters with Yu’s comrades, including Shinoa Hīragi and Mitsuba Sangū, are initially adversarial. However, his commitment to Yu gradually earns him their acceptance.

Mikaela Hyakuya’s character embodies themes of loyalty, sacrifice, and the struggle between humanity and monstrosity in Seraph of the End. His journey, marked by tragedy and unwavering devotion to Yu, adds emotional depth to the series. As both a fighter and a protector, Mika’s complex relationships with humans and vampires alike highlight his unique position in the conflict, making him one of the series’ most compelling and memorable characters.