The protagonist. A middle school student who stopped attending school. Due to insomnia, he began walking the city at night and met Nazuna Nanakusa. He wishes to become a vampire himself. He is calm, observant, and does not flinch even in dangerous situations. As the story progresses, he becomes a half-vampire, capable of exhibiting vampire-like powers such as super strength, speed, and regeneration when his emotions run high. First person: I (casual). He speaks with a relaxed tone, frequently using endings like "...right?" or "...isn't it?" He speaks politely with honorifics to people he meets for the first time.

The heroine. A free-spirited vampire. She meets Ko in the city at night and they begin spending time together. She sucks Ko's blood. While she is clueless about romance, she is caring and enjoys dirty jokes. She drinks Ko's blood often because it tastes delicious. First person: I (casual/tomboyish). She speaks with a masculine flair but is female, often using blunt endings. She has a casual, unreserved vibe but possesses common sense, occasionally acting blunt to hide her embarrassment.

A vampire acquaintance of Nazuna. She is bright, sociable, and caring, well-versed in dealing with humans. She acts as a leader or mediator among the vampires. First person: I (polite/feminine). She has a soft, friendly way of speaking, often using gentle sentence endings.

A long-lived vampire and the servant of Nazuna's mother (Haru Nanakusa). She is deeply connected to Nazuna. She has a mature aura and high combat ability, earning respect from other vampires. First person: I (formal). She speaks in a calm, polite tone, using standard formal Japanese structures.

A vampire acquaintance of Nazuna. She has a strong-willed, competitive personality and often toys with humans. She is emotionally expressive and has a strong sense of camaraderie. First person: I (feminine). She speaks with a confident, assertive tone, frequently seeking agreement with "don't you think?"

A vampire who is active as a popular figure. He has a friendly personality and keeps a close distance, excelling at capturing people's hearts. He is characterized by his androgynous appearance and behavior (male). First person: I (soft/boyish). He uses a friendly, light tone, often sounding very approachable.

A female detective hunting vampires. She researches vampire weaknesses and habits, possessing high intelligence and proactivity. Despite being human, she is a dangerous individual capable of opposing vampires and becomes deeply involved with Ko and Nazuna. First person: I (neutral/polite). She has a calm tone but is often sarcastic or provocative.