Naoya Kirihara is the younger of the two Kirihara brothers at the heart of the Night Head story. He was born with a powerful combination of psychic abilities, including clairvoyance, telepathy, precognition, and a rare healing power. These gifts, however, come at a severe cost. Any physical contact with another person or an object can force him to experience traumatic visions, often leaving him in a state of catatonia that can last for an extended period. The sole exception to this overwhelming sensory overload is his older brother, Naoto, whose touch does not trigger any harmful visions. Because of this, Naoya depends entirely on Naoto for stability and protection. He habitually positions himself behind his brother, using him as a shield to prevent accidental contact from others. As a child, he would follow Naoto by holding onto the back of his jacket, and he continues to address Naoto with the affectionate term "Nii-san."

Abandoned by their parents after their supernatural abilities became apparent, Naoya and Naoto were confined to a research facility for fifteen years. Their eventual escape marks the beginning of their journey into a world that fears and misunderstands them, and they soon learn that their powers are tied to a prophesied Upheaval that will reshape reality. Naoya’s motivations are closely tied to his desire for a normal life and his deep need to stay near his brother. He is the more sensitive and vulnerable of the two, often overwhelmed by the information his mind cannot filter. His role in the story is that of a reluctant seer whose visions guide the brothers’ actions and reveal hidden truths, while his healing power provides a rare source of hope for others.

Throughout the narrative, Naoya undergoes subtle development as he begins to accept his abilities rather than merely endure them. His bond with Naoto remains the central relationship in his life, and he often acts as the emotional anchor that tempers Naoto’s more fiery temperament. In addition to his psychic senses and healing touch, Naoya possesses the potential for even greater power, hinted at in both the original Night Head Genesis anime and the later Night Head 2041 adaptation. His outward appearance varies between versions—depicted with black hair and brown eyes in Night Head Genesis, and with white hair and red eyes in Night Head 2041—but his core character as a gentle, traumatized young man who learns to find strength in his connection to his brother remains consistent.