The protagonist. A middle school dropout who started walking the city at night due to insomnia, leading to his meeting with Nazuna Nanakusa. He wishes to become a vampire himself. He is calm, observant, and doesn't flinch 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). He speaks with a blunt tone, often 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 hanging out together. She drinks 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/feminine). She speaks with a somewhat masculine, rough tone, frequently using casual endings. She is unreserved and has a lighthearted vibe, but she possesses common sense and can be blunt or shy to hide her embarrassment.

A vampire acquaintance of Nazuna. She is bright, social, 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 (polite). She speaks in a calm, formal tone, using polite endings like "...is it not?" or "...shall we?"

A vampire acquaintance of Nazuna. She has a strong, competitive personality and often toys with humans. She is emotionally expressive and has a strong sense of camaraderie with her peers. First person: I (casual/feminine). She uses a confident, assertive tone, often asking rhetorical questions.

A vampire who is active as a popular figure. He has a friendly, high-touch personality and is skilled at winning people's hearts. He is notable for his androgynous appearance and behavior (he is male). First person: I (soft/boyish). He uses a friendly, light tone, often speaking very casually.

A female detective hunting vampires. She researches 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). She speaks in a calm tone but uses a lot of sarcasm and provocation.