The protagonist. A middle school student who stopped attending school. Due to insomnia, he starts walking the city at night and meets Nazuna Nanakusa. He wishes to become a vampire himself. He is calm, observant, and remains unfazed even in dangerous situations. As the story progresses, he becomes a half-vampire, manifesting powers like superhuman strength, speed, and regeneration when his emotions run high. First person: I (casual/masculine). He speaks with a blunt, informal tone, frequently using endings like "...da na," "...daro," or "...jan." 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 drinks Ko's blood. While she is clueless about romance, she is caring and enjoys dirty jokes. First person: I (casual/feminine). She speaks with a rough, boyish tone, often using endings like "...jan," "...daro," or "...da na." She is unreserved and lighthearted, but possesses common sense and can be shy or blunt to hide her embarrassment.

A vampire acquaintance of Nazuna. She is cheerful, 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 endings like "...yo" or "...ne."

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/feminine). She speaks in a calm, polite tone, using endings like "...desu ne" or "...deshou."

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 (standard/feminine). She has a confident tone, frequently using endings like "...janai?" or "...desho."

A vampire who is active as a popular figure. He is friendly and tends to get physically close to others, excelling at capturing people's hearts. He is characterized by his androgynous appearance and behavior (male). First person: I (soft/masculine). He uses a friendly, light tone, often using endings like "...dayo" or "...jan."

A female detective hunting vampires. She has researched vampire weaknesses and habits, possessing high intelligence and initiative. Despite being human, she is a dangerous individual capable of opposing vampires and becomes deeply involved with Ko and Nazuna. First person: I (standard/feminine). She has a calm tone but uses a lot of irony and provocation, often using endings like "...ne" or "...desho."