Naomi Otoya is a high school student and a supporting character in Grand Blue Dreaming. He works part-time as a kitchen staff member at the same restaurant as Iori Kitahara and Sakurako Busujima. At his school, Naomi serves as the captain of the diving club, reflecting his strong passion for diving. Physically, he is a slender teenage boy with shoulder-length blond hair that falls in bangs over his forehead, complemented by brown eyes. His appearance is often described as strikingly handsome, frequently leaving others in awe.

Naomi's personality is generally cheerful and lively, with a natural inclination to ensure everyone around him enjoys their diving experiences. At the same time, he is calm, gentle, and easy to get along with, making him approachable. He carries a sincere and earnest demeanor, and he deeply admires Iori Kitahara, viewing him as a role model. Both Iori and Sakurako initially perceive Naomi as innocent and somewhat naive, even considering him a vulnerable target for the opposite sex. This perception is challenged when Naomi rejects a romantic confession from Sakurako, an event that strongly implies he is gay and harbors romantic feelings for Iori instead. This revelation marks a meaningful character beat, suggesting a hidden depth to his otherwise straightforward and cheerful exterior. Naomi's motivations center on his love for diving and his desire to improve, and his role in the story often involves interacting with the main cast at work and through diving activities, contributing to the series' comedic and character-driven moments.