Mizuha

The Constructed Perfection
Her natural disposition is one of great dedication and responsibility. She's the class president, a talented swimmer, and an excellent student. However, these traits aren't genuine passions; they're a "duty" to fulfill her mother's expectations. Therefore, she's very good at hiding her feelings, sometimes appearing indifferent.
The yearning for freedom and resistance (Suppressed Rebellion)
Deep down, Mizuha is rebellious and wants to defy her mother's orders. This frustration causes her to quickly become infatuated with Fushi (an entity free from rules), because Fushi is what she wants to be but cannot be.
Obsessive Love
When Mizuha loves someone, she loves them "completely" and develops a possessive personality. She wants to be the only person most important to Fushimi. This trait gradually develops into a terrifyingly jealous, even yandere-like behavior, partly influenced by the genetic predisposition of her "Hayase" bloodline, which passed down her obsession with Fushimi.
A state of mental fragmentation.
After she starts losing her sense of self to Knocker, her personality will begin to "swing" (mood swings):
At times, they can look sad and pitiful, like a lost child.
Sometimes they can be excessively cheerful to the point of being creepy (Manic).
At times, they will display cruelty and coldness.
An loneliness that no one can fill.
Her saddest trait is "her distrust of the love of those around her." She feels that her friends love her only for her outwardly capable appearance, but no one truly loves her distorted inner self, except for Fushi, whom she sees as the only one who accepts her.

Mizuha and Fushi – A passion that turned into a tragedy.
Role: Mizuha sees Fushi as a "way out" from her boring and stressful life. She falls deeply in love with him to the point of obsession.
Relationship: For Fushi, Mizuha is a friend he pities and wants to protect. However, Mizuha's love is too heavy. Their relationship becomes distorted when Mizuha demands that Fushi only sees her, leading her to accept Nocker into her body in order to "become superior" to other humans and stand by Fushi's side.
Mizuha and her mother – the cause of the rift.
Role: Mizuha's mother represents pressure and control.
Relationship: It's a relationship filled with awkwardness. Mizuha tries to be the "perfect daughter" to please her mother, but at the same time, she hates being controlled. This pressure weakens her mind, making her easily susceptible to Knocker's manipulation.
Mizuha and Hayase (Bloodline and Curse)
Role: Mizuha is a descendant of Hayase (Fushimi's ancient sworn enemy).
Relationship: Despite being born in different eras, Hayase's spirit and madness still flow through Mizuha via Nocker. This relationship is a "curse" that prevents Mizuha from living a peaceful life like a normal teenager, because she is destined to be attached to Fushi.
Mizuha and her school friends (Kahaku and others).
Role: She is the class president and a model student admired by everyone.
Relationships: It's a "superficial" relationship. Her friends see her as perfect, but no one truly understands the loneliness and darkness within her. The admiration her friends show only makes Mizuha feel more isolated, because she feels no one loves her "true self."
Mizuha and the Knockers – a dangerous alliance.
Role: Knocker uses Mizuha as a tool for communication and to destroy Fushimi from within.

Relationship: It's a complex parasitic relationship. Nocker gives Mizuha "courage" and "power" to do things she never dared to do before (like rebelling against her mother), but it gradually erodes her sense of self, until ultimately she can't distinguish whether the feelings she's experiencing are hers or Nocker's.

Physical Appearance and Proportions
Appearance: Mizuha is described as a slim and athletic-looking girl, as she is a standout member of the swimming club.

Face and Hair: She has a neat and beautiful face, typical of a "model student," with long black hair that is usually tied back with a hair tie adorned with a feather, which is her signature look.
Bloodline resemblance: Her appearance is strikingly similar to that of her ancestor, Hayase, to the point that Fushi sometimes feels confused or nostalgic for the past whenever she sees her face.
Clothing (Attire)
High school uniform: This is the main outfit we see her wearing most often. It consists of a long-sleeved shirt and a short plaid skirt, or a modern Japanese school uniform, which promotes her image of cleanliness and orderliness.

Swimsuits: As a member of the swimming club, we'll see her in either a school swimsuit or a competition swimsuit, which emphasizes her toned physique and athletic build.
Feather accessories: These are an important item she always wears in her hair, whether in her school uniform or casual attire. They may symbolize some kind of bloodline or family ties.
Visual Representation (presentation through body and emotions)
Suppressed Perfection: Her body and personality were designed to appear "flawless" to reflect the pressure from her mother to be number one in everything.

Changes when possessed by Nocker: As Nocker begins to gain control of her body, her physical expressions will change, such as having an empty or distorted gaze and a more threatening demeanor, which contrasts with the neat school uniform she wears.

Residence: Yanagi Household
Mizuha's residence wasn't just a house; it was a "golden cage" that reflected her status and the expectations placed upon her.

House characteristics: It's a middle-to-upper-class residence in modern Japan. The house is spotlessly clean and tidy, almost to the point of being intimidating (reflecting her mother's personality).
Mizuha's bedroom: It's a simple room with only a few school supplies and essential items. This is the only place she hides her feelings, but at the same time, she doesn't feel safe there because her mother always spies on her and controls her life.

The atmosphere in the house: Filled with silence and tension. Mizuha has to act like the perfect daughter at all times while living in this house, so she often tries to find excuses to go outside or to school to escape the atmosphere at home.
School: High School
School is where Mizuha plays a social role, and it's where she first met Fushi.

School Role: Mizuha is a top student, known as a star swimmer, and also the class representative, making her a focus of attention from teachers and other students.
Swimming Club: The school swimming pool is an important place because it's where Mizuha can fully showcase her physical abilities, and it's also where Fushimi often comes to observe her.

Rooftops and building corners: In the story, we see Mizuha using quiet areas in the school to talk to Fushi, or as places where she begins to exhibit abnormal behavior from being possessed by Nocker.
The significance of the place.
The conflict between two worlds: home is where she must "submit" to her mother, while school is where she must "maintain reputation" and maintain perfection.

The beginning of a transformation: Both home and school become mental battlefields when Fushi and Nocker enter her life. The once safe and orderly spaces gradually crumble, along with her own mental state.