Dr. Atsushi Hirata is introduced as the new counselor and therapist for Tarou Komori, the protagonist of the story. A clinical psychologist associated with Tokyo University, Dr. Hirata brings an air of academic authority and professional curiosity to the rural setting. He is portrayed as somewhat eccentric, a personality trait that complements his deep fascination with the workings of the human mind.

His primary motivation is rooted in his professional interests. While treating Tarou, he becomes particularly interested in the boy's dreams and psychological condition, seeing them as a potential source of support for his own theories. Dr. Hirata is the primary conduit for much of the psychological and neuro-scientific terminology that the narrative explores, often explaining complex concepts related to consciousness and trauma.

In the story, Dr. Hirata serves as a grounding, scientific voice amid increasingly mysterious and supernatural events. His role is to provide a rational counterpoint, initially dismissing Tarou's out-of-body experiences as mere altered states of consciousness rather than anything paranormal. However, as the events in the town of Suiten escalate, his stance evolves. He begins to concede that a supernatural component may be at play, specifically suggesting that the land and mountain surrounding the town could be a trigger for these unexplained phenomena.

His key relationships center on his professional interactions. He works directly with Tarou and frequently meets with Tarou's parents, Ryoya and Miki Komori, to discuss the boy's progress and the strange occurrences. He also collaborates with Dr. Reika Otori, a fellow researcher, and together they provide the characters and the audience with extensive information on brain function and memory.

Throughout the series, Dr. Hirata undergoes a significant development in his worldview. He shifts from a strict scientific skeptic to a professional who acknowledges the potential for genuine supernatural forces. Privately, he himself experiences supernatural events, though he tends to keep these experiences to himself, preferring to analyze them through the diagnostic framework of psychological alterations. This internal conflict between his scientific training and his personal experiences defines his character arc.

His notable abilities lie not in physical action but in his intellect and professional skills. He is highly knowledgeable about clinical psychology, neurobiology, and conditions like narcolepsy and post-traumatic stress. This expertise allows him to introduce therapeutic techniques, such as E.M.D.R. therapy, and to help the characters process their trauma from a scientific perspective, even as the world around them becomes increasingly inexplicable.