Kouki Yukishiro

Kouki is timid, insecure, and deeply affected by a loss of self-worth. She remembers being praised as a gifted child and struggles with the contrast between that recognition and her later sense that she has become invisible to everyone around her.

Her isolation makes validation extremely important to her. She wants to be noticed again but lacks the confidence and social support to pursue that desire in a healthy way. This vulnerability allows another person to exploit her shame and push her toward actions she would not otherwise choose.

Kouki is not naturally malicious. When confronted by Momo's group, much of her aggression comes from fear, humiliation, and coercion rather than genuine hatred. She is capable of remorse and gradually becomes more comfortable accepting help.

Music remains central to her identity even after she stops playing publicly. Her relationship with the piano is tied to both her greatest pride and deepest insecurity, making the recovery of that skill an important part of her later development.

Kouki is a gifted pianist with perfect pitch. She describes sound in unusually visual terms, a talent associated with her synesthesia, and can accurately recognize and reproduce musical notes.

After being cut with a supernatural kozuka knife, Kouki gains the ability to perceive pygmy-like entities and becomes connected to supernatural power. The pygmies assist her by constructing objects and responding to her needs.

She later obtains the Lord of the Flies ability, which allows her to control small living creatures through piano performance. The power can coordinate enormous numbers of tiny organisms, turning her music into a form of battlefield command.

Her musical ability makes the technique particularly effective because she can precisely control her performance while simultaneously perceiving sound at an exceptional level.

The Lord of the Flies power can also enhance allied supernatural effects. Kouki's performance amplifies Rin Sawaki and Mai Kawabanga's abilities during a later battle.

Kouki was celebrated as a piano prodigy during childhood. Strict training from her mother gradually strips the joy from playing, and a defeat in competition against Aira Shiratori contributes to her abandoning the piano.

By high school, she feels overshadowed socially and within her own family. After posting an intimate photograph of herself online in a desperate attempt to receive attention, she is identified and blackmailed by Takeshi Murakami. He orders her to steal Momo's supernatural power using a kozuka knife.

Kouki attacks Momo at school with the assistance of the pygmies. Okarun and Aira become involved, and the History and Culture Research Club eventually realizes that Kouki is being coerced rather than acting independently.

The group begins protecting and monitoring her in an attempt to identify the blackmailer. This pulls Kouki deeper into the conspiracy surrounding Murakami, Saint-Germain, the kozuka knives, and the collection of supernatural abilities.

Her later return to piano performance allows her to wield Lord of the Flies and fight alongside Rin and Mai, transforming the talent she had rejected into a means of protecting other people.

Alice Yukishiro is Kouki's younger sister. Kouki's perception that Alice has surpassed her contributes to her insecurity and sense of being overlooked within her family.

Aira Shiratori competed against Kouki in piano competitions during childhood. Kouki's defeat contributed to her abandoning the instrument, making their later reunion emotionally difficult.

Momo Ayase is initially Kouki's target under blackmail. Momo and her friends later recognize Kouki's circumstances and try to help her.

Ken Takakura helps confront Kouki during her attacks on Momo and later participates in efforts to uncover who is controlling her.

Rin Sawaki becomes one of Kouki's closest allies during the later supernatural conflicts, with their music-based abilities proving compatible.

Mai Kawabanga fights alongside Kouki and Rin.

Kinta Sakata helps monitor Kouki using nanoskin technology while the group searches for her blackmailer.

Takeshi Murakami blackmails Kouki and manipulates her into attempting to steal Momo's power.