Live action TV
Description
Kayoko Kotohiki is a student from the third-year class of Shiroiwa Junior High School, a fictional school located in Kagawa Prefecture in the source novel and manga. She is a fifteen-year-old girl with a petite build, standing at 154 centimeters and weighing around 50 kilograms. Her physical appearance includes straight, dark shoulder-length hair, which she would secure with a dark blue hair clip when dressed in a kimono for formal events, and she is described as never wearing makeup. Her blood type is B.

Before the events of the Program, Kayoko was a member of her school's tea ceremony group, though her teacher considered her to be more energetic and playful than elegantly refined, which was the traditional expectation. In the manga adaptation, her extracurricular activity is changed to ikebana, the art of flower arranging, which she practiced in a cultural center located below the dojo where her classmate Hiroki Sugimura trained in martial arts. She developed a crush on a nineteen-year-old man, the grandson of a school director who sometimes led the tea ceremony, and she reflected on their two brief encounters. The manga also adds more detail to her home life, where it is mentioned that her mother was her father's mistress and that Kayoko sometimes worked as a waitress at the bar her mother ran.

Kayoko's personality is defined by an initial cheerfulness and energy, traits that her tea ceremony teacher felt were at odds with the required elegance of the practice. In the manga, she admits to having been afraid of Hiroki Sugimura because of his intimidating martial arts training, but a key moment where she helps him care for a distressed kitten on a school bus reveals her compassionate side to him and allows her to see his gentleness. This incident, in which she uses her knowledge of caring for her own three kittens at home to solve the problem, also demonstrates a practical and nurturing nature.

Once the Program begins, Kayoko's central motivation shifts almost entirely to survival, and her strategy is one of complete isolation. She spends the majority of the game hidden in one location, refusing to move unless forced by the announcement of a new danger zone. Her fear is so overwhelming that she stays awake at all times to avoid being caught off guard, leading to extreme physical and mental exhaustion from hunger, thirst, and sleep deprivation by the final day. This state of terror dictates her actions when she is finally confronted by another person.

Her role in the story is almost entirely tied to her classmate Hiroki Sugimura, who is secretly in love with her and spends the Program searching for her with the intention of protecting her and helping her escape. Kayoko remains unaware of his feelings or his quest and therefore reacts to him as she would any other potential threat. When an injured Sugimura locates her using a tracker, her panicked response is to fire her assigned weapon, which in the novel is a Smith & Wesson M59 automatic pistol, and in the film is a SIG-Sauer P226. In the novel and film, she shoots him repeatedly, killing him. As he lies dying, Sugimura confesses his love to her and gives her instructions on how to find a group of classmates who would help her escape. Before she can follow his directions, she is shot and killed by the psychotic Mitsuko Souma, who had been drawn by the sound of the gunfire.

Her character arc is a tragic one, demonstrating how the brutal conditions of the Program can transform even a normally cheerful student into a terrified individual who accidentally destroys the very person trying to save her. Her development is defined by her gradual breakdown from a lively girl into a paranoid, sleep-deprived survivalist, culminating in the devastating realization of her fatal mistake, which comes only after it is too late. The manga adaptation offers a slightly different development for her. In this version, when Sugimura finds her and disarms himself to prove his trustworthiness, she lowers her weapon and they briefly reconnect, sharing a plan to escape. However, this hopeful development is cut short when they are both killed by the class's most lethal student, Kazuo Kiriyama.

In terms of abilities, Kayoko does not possess any combat training or specialized survival skills. Her most notable ability in the story is her capacity to remain hidden for an extended period, effectively using concealment as her primary defense. Her designated weapon is a handgun, but she demonstrates no proficiency with it, using it only once in a blind panic with fatal consequences. Her practical knowledge, shown in the manga's kitten rescue scene, highlights her competence in caregiving tasks rather than any form of combat or aggression.
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