Mahiru Seki

Mahiru Seki is a side character in Call of the Night. He's a childhood friend of Kou Yamori and Akira Asai who is in love with the vampire Kiku Hoshimi and, like Kou, wants to become a vampire himself to escape his everyday life.

Appearance
Mahiru is a young boy with a darker faint skin tone who usually wears his school uniform consisting of a gray blazer, under which he wears a red hoodie, gray pants, and white tennis shoes. His hair is dark blonde and tied in a little ponytail.

After choosing to become a vampire, he lets his hair down and starts to wear baggy clothes, described by Kou as "looking tired."

Personality
Mahiru is a kind person that tries to keep a good and relaxed atmosphere with the people around him, able to socialize with his classmates and teachers, making him very popular in school.

But that's a facade under which lies a depressed and traumatized person who resents his family for the emotional abuse they put him through. Similar to Kou and Akira, his only genuine friends, socializing with his schoolmates is not fun to him. He is tired of constantly being pressured to spend time with them and feels great after telling them the truth, despite getting beaten up by them. Mahiru used to be a very shy and quiet child but started to copy his brother's personality after he died.

After spending time with Kiku Hoshimi, Mahiru undergoes a drastic personality change, becoming rude, blunt, violent, and excited about killing humans in the future. However, he seems to have mellowed out after fighting with Kou. His depression is much more apparent; his words often have a melancholic undertone, and he isolates himself from everyone except Kiku. Despite being willing to abandon his friends and family, he is still attached to Kou and Akira.

Kou Yamori
Kou and Mahiru are childhood friends. Mahiru felt like he could be himself around Kou when they were little. Despite that, he kept copying his brother's personality and didn't tell Kou the truth about his family. They understood each other well, and Mahiru often thought of him after Kou dropped out of school. After Akira was assaulted by a vampire, Mahiru opposed the idea of Kou becoming one and scolded him. Later, he learned to accept it and offered Kou to drink his blood in case he became a vampire. While initially confused by Kou's lack of hesitation, he soon understood Kou. He used it as a motivator to become a vampire himself, even proposing they compete over who gets to become one first.

After he decided to become Kiku's servant, their relationship took a drastic turn for the worse. He enjoyed toying with Kou as they talked and kept creeping him out with his radical personality change. He felt upset when Kou took Anko Uguisu's side and suggested that Mahiru was just being used by Kiku, beating him up. When Kou turned into a half-vampire and almost killed him, Mahiru felt betrayed because Kou didn't tell him about his powers before and revealed that he was incredibly jealous of him for "being special," ending their friendship on the spot.

He later gives him an indirect hint of where he's headed, seemingly inviting Kou, and is shown to still care about him as he values a photograph of himself, Kou and Akira too much to burn it. It's revealed that Mahiru regrets how he treated Kou and is happy that he came to see him. However, because of a misunderstanding, Mahiru is scared of Kou and thinks he wants revenge, causing him to run away from Kou in fear.

Kiku Hoshimi
Mahiru is in love with Kiku. She tells him the words he wants to hear and listens to everything he has to say, including his worries, making him feel fulfilled and understood, staying with her even after she is revealed to be a vampire, despite witnessing a vampire almost kill a person before. Thanks to Kiku's manipulation, Mahiru is willing to leave behind everyone he knows and wants to protect her life and secrecy at all costs. He is shown to be frustrated because she still hasn't turned him into a vampire, but he said that, while he'd like to become one, Mahiru is fine with it not happening as long as he gets to stay at Kiku's side.

He is not entirely himself because of Kiku's vampiric charm, which, as he describes, decreases his capability to think and puts him in a euphoria. Despite his loyalty, he is willing to go against her wishes and secretly keeps a photo from his past even though Kiku wants him to burn his past belongings. He also isn't afraid to confront her if he notices her keeping secrets, insisting that Kiku talk to him properly.

Akira Asai
Like Kou, Mahiru is a close friend of Akira. He wasn't initially close to her, calling her an idiot. Still, they eventually became genuine friends, feeling a connection they didn't have with anyone else due to their similarities. She, along with Kou, is one of the most important people in his life. They hung out at school, and Mahiru talked with her about the things going on in his life, like dating someone. After Akira almost got killed by a vampire, his opinion of vampires turned negative for a while, and he didn't want Kou to become one. He consulted Akira about becoming a vampire and shared his worries with her. After joining Kiku, he was still on relatively good terms with her before bidding her farewell. As he burned his past belongings to eliminate his future vampiric weaknesses, he looked at a photo he had taken with Akira and Kou and decided to keep it.

Mrs. Seki
After his brother's death, Mahiru was constantly neglected by his mother, who kept hoping that he would return one day. Ever since that happened, Mahiru's room was never changed and still looks like the typical room of an elementary school student. Mahiru wasn't allowed to go on a school trip because "his brother wasn't going." This treatment caused Mahiru's frustrations to build up and eventually turn into silent resentment. He still cared about his mother, helped his parents in the flower shop, and made excuses for his mother's abusive behavior, believing she was broken from the shock.

After Kiku confronted her and explained that she was aware that Shougo was dead but didn't want to accept it, Mahiru reflected on his past and confessed to his mother that he used to hate her to the point of feeling exhausted but that he doesn't feel that way anymore. He explained that he now felt nothing for her and used the opportunity to taunt her with a smile before leaving his family for good.

Abilities
As an average human, Mahiru doesn't possess any extraordinary abilities.

Quotes

 * "Farewell, mom. Don't worry, I'm sure, Nii-san will come back. Just stay patient, like you've been until now."
 * "Cleaning up my personal affairs before becoming a vampire is a lot like preparing for suicide, huh..."