Natsuhiko Hyuga is a second-year student at Kamome Academy's high school division and a member of the school's broadcasting club. He presents himself as a flashy, lively, and self-centered individual who enjoys fishing, karaoke, and flirting, often brazenly asking girls for their contact information shortly after meeting them. This demeanor makes him appear shallow and narcissistic at first glance, though he is not unfriendly. His underlying motivations are tied to a deep and seemingly one-sided devotion to Nanamine Sakura, whose cold and dismissive treatment of him he interprets as a form of special attention. This attachment drives him to align himself with Tsukasa Yugi and Sakura, making him a secondary antagonist who assists in their schemes.

Natsuhiko is ultimately revealed to be far more than an ordinary human. He is linked to the rumor of the human who cannot die no matter how many times they are killed, possessing a form of near-immortality. Additionally, his blood is poisonous to supernaturals, making him a dangerous figure. These abilities mark him as a mysterious and formidable entity within the supernatural hierarchy of the school. In the narrative, he functions as a key operative for Tsukasa's agenda, often facilitating the manipulation of rumors or carrying out tasks that threaten the balance between the human world and the supernatural. His role complicates the conflict, as he interacts with the protagonists while maintaining his allegiance to more antagonistic forces.

Natsuhiko's key relationships are defined by his unwavering loyalty to Sakura and his cooperative role with Tsukasa. His interactions with the main characters, such as Nene Yashiro, involve trickery and putting them in danger, but he does not seem to hold any personal ill will toward them. His character develops from a seemingly comedic background player into a pivotal figure with significant implications for the series' lore. The mystery surrounding his true origins, the extent of his powers, and his connection to the deeper history of Kamome Academy continues to be a point of intrigue as the story progresses.