Mahiru Seki

Mahiru Seki is a side character in Call of the Night. He's the childhood friend of Kou Yamori and Akira Asai, and is in love with the vampire Kiku Hoshimi, wanting her to turn him into a vampire.

Appearance
Mahiru is a young boy with a darker faint skin tone who usually wears his school uniform that consists of a gray blazer and gray pants under which he wears a red hoodie, plus white tennis shoes. His hair is a dark blonde and tied to 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 very unhappy 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 change in personality, becoming rude, blunt, violent and excited about killing humans once he becomes a vampire. Despite being willing to abandon his friends and family, he is shown to still be 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 still kept copying his brother's personality and didn't tell him the truth about his family. They understood each other well and Mahiru often thought of him after he dropped out of school. After Akira got assaulted by a vampire, Mahiru was opposed to the idea of Kou becoming one and scolded him because of that. Later, he learned to accept it and offered Kou to drink his blood once he became a vampire and while he was initially confused by Kou's lack of hesitation, he soon understood why and even proposed that they compete over who gets to become a vampire 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 chance in personality. He felt upset when Kou took Anko Uguisu's side and suggested that Mahiru was just being used by Kiku, beating him up because of that. 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 gave him a indirect hint of where he's headed towards, seemingly inviting Kou, and is shown to still care about him as he valued a photograph of himself, Kou and Akira too much to burn it.

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 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 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. It's been theorized that he may not fully be himself because of Kiku's vampiric charm.

Akira Asai
Like with Kou, Mahiru is a close friend of Akira. He wasn't initially close to her, calling her an idiot, but they eventually became genuine friends, feeling a connection that they didn't have with anyone else, due to how similar they are. She, along with Kou, is one of the most important people in his life. After Akira almost got killed by a vampire, his opinion on vampires turned negative for a while and he didn't want Kou to become one. After joining Kiku, he was still on relatively good terms with her before bidding her farewell. As he burned his past belongings in order to get rid of his future vampiric weaknesses, he looked at a photo he took with Akira and Kou and decided to keep it.