Haruka Kotoura is the central protagonist of her story, a fifteen-year-old high school girl who possesses the involuntary ability to read the minds of those around her. This power, which she cannot control or turn off, has been the defining force of her life since early childhood. As a young, cheerful girl, she did not understand her peculiar gift and would innocently blurt out the private thoughts and secrets of her friends, teachers, and family members, not realizing that these were truths meant to remain hidden. This led to her being branded a liar and an outcast, resulting in relentless bullying and the complete erosion of her social circle. The strain proved too much for her family; after she inadvertently revealed that both of her parents were having affairs, their marriage collapsed, culminating in her mother uttering that she should never have given birth to her and abandoning Haruka to the care of her wealthy grandfather.

As a result of this profound childhood trauma, Haruka developed a cold, withdrawn, and defensive exterior, having concluded that she brings nothing but misfortune to those who get close to her. At the start of her high school years, she is extremely introverted and resigned to a life of solitude, attempting to keep everyone at a distance to protect both herself and others from the pain her ability causes. She tends to blame herself for every negative situation and has a tendency to spiral into self-destructive胡思乱想, believing that running away will solve everyone else's problems. Despite this, she is inherently good-hearted and shows glimmers of her former self when she feels safe. She has a sweet tooth, is notably bad at singing to the point of being called tone-deaf, lives alone and can cook for herself, though she struggles with keeping her room tidy.

Haruka's role in the story is driven by her search for acceptance and a place where she belongs. This begins when she transfers to a new school and meets her classmate Yoshihisa Manabe, a boy whose mind is an unusual oasis of simplicity and who is completely unfazed by her power. His initial thoughts are often bizarre and perverted, but his actions are always kind and loyal, and he offers her unconditional friendship with the promise to always stay by her side, a vow no one had ever made to her before. Through Manabe, she is recruited by Yuriko Mifune, the president of the school's ESP Research Club, who sees Haruka's ability as proof of the supernatural phenomena her late mother was persecuted for. Reluctantly at first, Haruka becomes the core member of the club, and through shared adventures and conflicts, she gradually forms her first genuine friendships with Manabe, Mifune, the stoic vice-president Daichi Muroto, and eventually even Hiyori Moritani, a jealous classmate who initially bullies her for her closeness to Manabe.

The character's development is a slow process of healing and learning to trust again. Over the course of the narrative, Haruka transitions from a girl who hides in cardboard boxes to avoid interaction to someone who can openly express her feelings and fight for her friends. She develops a deep affection for Manabe, though her romantic progress is complicated by his perverted thoughts and her own deep-seated insecurities, including a complex about her small stature and breast size. A significant milestone in her journey is the reconciliation with her mother, where she discovers that her mother's rejection was not born of hatred but from a fragile inability to face her own guilt and perceived failure as a parent. Her signature ability is an omnidirectional telepathy that reads not only surface thoughts but also visual images, memories, and delusions. However, this power requires her to be in the presence of the person to attribute the thoughts correctly, and she cannot distinguish between a person's voiced words and their internal monologue, a flaw that caused much of her childhood suffering.