Naru Arata is a thirteen-year-old girl living on the island of Iwato Jima in Okinawa. She is the childhood friend of the protagonist, Ao Fukai, and is considered the heroine of the story. Naru lives with her father, Mitsuo Arata, her younger sister, Miyu, and her grandmother; her mother died several years earlier during a Scub Burst event on the island. As a result of that same incident, which also involved the appearance of a mysterious Sea Giant, Naru became physically frail and requires the use of an inhaler or oxygen therapy to manage her breathing. However, the accident also awakened within her a yuta power, a psychic ability rooted in Okinawan folklore.

Despite her physical weakness, Naru possesses a resilient and strong-willed personality. She is kind, supportive, and remains loyal to Ao, often acting as his closest confidante on the island. Her motivations are closely tied to the unresolved trauma of the accident: she harbors a deep, almost longing connection to the Sea Giant that protected her during the event, and she later sees a reflection of that figure in Ao’s IFO, the Nirvash. This emotional link drives her involvement in the larger conflict surrounding the Scub Coral and the Secrets.

In the story, Naru serves as both an emotional anchor for Ao and a key figure whose yuta abilities become significant to the unfolding mysteries. Her relationships are primarily centered on her family and on Ao, though her bond with the Sea Giant and the supernatural dimensions of her power place her in a unique position within the narrative. Over the course of the series, Naru grapples with the implications of her abilities and her past, influencing both her own development and the events around her. Her notable abilities include extrasensory perception and psychic phenomena connected to the yuta tradition, which manifest as a direct result of the childhood accident that almost claimed her life.