Seri is one of several vampires Kou encounters after meeting Nazuna Nanakusa. Initially introduced as one of the more outgoing and teasing members of the vampire circle, Seri often acts the part of a party girl, fully embracing the gyaru lifestyle. However, underneath her confident front lies a growing sense of emptiness and emotional stagnation the kind that comes from decades of shallow pleasures and meaningless encounters.

Unlike some vampires who view turning humans as a necessity or convenience, Seri struggles with guilt about her influence on people who fall for her, especially when they’re willing to give up their lives just to be with her. This conflict comes to a head with Akiyama, a kind-hearted man she initially seduced, who later becomes one of the few people to truly understand her.

Seri has a flashy and attractive gyaru appearance, with wavy blonde hair, tanned skin, pierced ears, and bold makeup, including heavy mascara and lipstick. She often wears stylish, revealing outfits, like cropped tops, short skirts, and fashionable accessories, reflecting her desire to look trendy and maintain a fun-loving image.

Her expressions range from sultry and teasing to unexpectedly melancholic, depending on her emotional state. Even in her more light-hearted moments, there is a subtle sense of weariness in her eyes especially when she’s alone or reflecting on her past.

At first glance, Seri appears to be loud, confident, and flirty, enjoying playful banter and teasing others especially Kou. She is sarcastic and outgoing, with a wild streak that makes her seem untouchable. However, her demeanor is largely a front for emotional exhaustion and loneliness. As a vampire, she has spent years indulging in fleeting relationships and pleasures that no longer bring her joy.

Seri is emotionally guarded and reluctant to form deep connections, fearing the pain of attachment and loss. However, when faced with sincere kindness or vulnerability particularly from Akiyama and later Kou she begins to open up. Underneath her flashy exterior is a woman who craves authenticity and struggles with her own identity as both a predator and a person.

• Introduction as a Vampire
  Seri is introduced as one of the vampires investigating Kou, originally with the intent of pressuring him into choosing a vampire partner. She stands out with her bold personality and relentless teasing, though her interactions with Kou quickly shift from intimidation to genuine conversation.

• Conflict with Akiyama
  Seri’s emotional arc becomes central when Akiyama, a human man she once seduced, confesses that he still wants to be with her. Seri pushes him away, fearing she’ll destroy his life as she believes she’s done with others. Their confrontation becomes tense until Kou intervenes, helping them communicate honestly. Seri’s acceptance of Akiyama’s feelings marks a turning point in her character, allowing her to consider the possibility of deeper bonds.

• Emotional Growth and Allyship
  After reconciling with Akiyama, Seri begins to shed her performative lifestyle and become a more genuine friend and ally to Kou and Nazuna. While she maintains her gyaru edge, she becomes more reflective and emotionally aware, offering advice and support when needed. She even participates in helping Kou during the events surrounding his transformation and journey to Hokkaido.