Mikaela Hyakuya/Relationships

Special Private Yūichirō Hyakuya
A member of the Japanese Imperial Demon Army. As the last surviving member of Mikaela's orphanage family, Mika is extremely protective over him. Rescuing Yu from the greedy humans is Mika's sole reason for living. Mika was fatally wounded while giving Yu an opportunity to escape when they were human. As a vampire, Mika is too surprised to stop Yu from stabbing him through the chest during the battle at Shinjuku. Yu stabs him through the back when Mika protects Yu's so-called friend, Sergeant Shinoa Hiragi, and he has a difficult time recovering from that severe of an injury. Mika has risked his life for Yu repeatedly and will even risk his life for the people Yu thinks of as friends. Mika hates the humans Yu is with, correctly believing them to be experimenting on and using Yu. Considering that the experiments made Yu try to kill his human friends, Mika is not wrong.

Third Progenitor and Queen of Japan Krul Tepes
Mikaela belongs to her sect. Krul intentionally disobeys orders to kill the Hyakuya orphanage children and takes Mika and his family underground to Sanguinem instead. If Krul did not take them from there, then Mika and his family would have been unethically and brutally used for experimentation by the Hyakuya sect, whom Krul claims to have killed off. Four years later, Krul transforms Mikaela into a vampire against his will, effectively saving his life and preventing Ferid Bathory from becoming his master. When Mika refuses to drink human blood, she allows Mika to live off of her blood, claiming that he is now her dog for all time. She enjoys his dependence on her and is the only character in the series so far who appears to enjoy being bitten.

Seventh Progenitor Ferid Bathory
The sadistic pedophile who kills Mikaela's family. Mika approaches him back when he was a human child. They sustained a relationship where Ferid bit Mika and drank his blood in exchange for providing good food and money to Mika. Mika steals a map and a gun from him and attempts to escape, but Ferid waits for them at the exit. He fatally wounds Mika, but Krul Tepes rips him apart and sends him away from Mika.

Once Mika is a vampire, Mika rebels against him often, even pointing his sword at Ferid's neck and cutting off his arm, but Ferid is too strong for it to matter. Ferid wants Mika to drink human blood to stop his growth at his most beautiful age. He presented Mika to the Progenitor Council as his favorite servant and stated Ferid could not bear to be away from him. He has physical contact with Mika every chance he gets and even touches Mika's bottom at one point, much to Mika's displeasure. He is the only vampire aside from Krul who knows much about Mika.

City Guard Lacus Welt
Lacus is a city guard that often works with Mika and René. He is impressed by Mika's power and is concerned about Mika refusing to drink blood, even when Mika's obviously thirsty. He often tries to start conversations with Mika, but Mika usually answers with silence.

City Guard René Simm
Lacus and Mika's coworker. He is always seen with Lacus. He accused Mika of stealing glory, but Mika said he could have it. Unlike Lacus, he is unconcerned with Mika's behavior and long as Mika does his job.

Sergeant Shinoa Hīragi
A member of the Japanese Imperial Demon Army's Moon Demon Company, whom Yu called his friend. Mika nearly died to protect her from Yu for that reason, but he claims she is just using Yu.

Lieutenant Colonel Guren Ichinose
A member of the Japanese Imperial Demon Army's Moon Demon Company, whom knew how to end Yu's transformation. Mika nearly killed him in battle, but Yu interrupted him.

Team Leader Aiko Aihara
Mika confronts her in Nagoya. He tries to convince her to play dead after she orders her team to commit suicide and he sticks his hand into her mouth to remove the pill she was about to take. After quickly coming to understand him, she tells him Yuichiro's location. She insists that he kill her because suicide would look too suspicious after they tricked the other vampires and give them false information, Mika refuses but she leaves him no choice but to kill her without ever learning her name, and looks a slightly sad for a moment afterwards.