The protagonist. A middle school dropout who, suffering from insomnia, began walking the city at night and met 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 super strength, speed, and regeneration when his emotions run high. First person: I (casual). Speaks with a blunt, boyish tone, frequently using sentence endings like "...daro" or "...jan." He speaks politely with honorifics to people he meets for the first time.

The heroine. A free-spirited vampire. She met Ko in the night city and they began spending time together. She drinks Ko's blood. While clueless about romance, she is caring and enjoys dirty jokes. She loves the taste of Ko's blood and drinks it often. First person: I (casual/feminine). Speaks with a somewhat boyish, rougher tone but is female, often using "...jan" or "...daro." She has a lighthearted, unreserved attitude but possesses common sense, occasionally becoming shy or blunt to hide her embarrassment.

A vampire acquaintance of Nazuna. Bright, social, and caring, she is well-versed in dealing with humans. She acts as a leader or mediator among the vampires. First person: I (polite/feminine). Speaks in a soft, friendly manner, often using feminine sentence endings like "...yo" or "...ne."

A long-lived vampire and the progeny 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). Speaks in a calm, polite tone, using formal endings like "...desu ne" or "...deshou."

A vampire acquaintance of Nazuna. Strong-willed and hates losing, she often toys with humans. She is emotionally expressive and has a strong sense of camaraderie. First person: I (casual/feminine). Speaks with a confident, assertive tone, frequently using "...janai?" or "...desho."

A vampire who lives as a popular figure. Friendly and physically affectionate, he is skilled at capturing people's hearts. He is notable for his androgynous appearance and behavior (male). First person: I (soft/masculine). Uses a friendly, light tone, often ending sentences with "...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 (polite/feminine). Speaks in a calm tone but is often sarcastic or provocative, using endings like "...ne" or "...desho."