Nagisa Saito is a part-time high school student employee at the Lemon Beach House restaurant, sporting tan skin, short indigo hair, and gray eyes. She is usually seen in the restaurant's uniform. A keen surfer, she also enjoys bike riding and jump rope, and watches magical girl and tokusatsu shows in her spare time. Her older sister, Aiko Saitō, debuted in manga before Nagisa, though Nagisa appeared first in the anime adaptation. Her friends Koike and Yamada are introduced later in the manga and visit Lemon for the first time in chapter 364. Nagisa stands out due to her pronounced fear of Ika Musume, whom she views as a legitimate threat to humanity. This contrasts sharply with others who dismiss Ika's invasion claims. Ika Musume frequently teases her, reinforcing Nagisa's anxiety. Nagisa attempts various strategies to reduce Ika's attention. She briefly adopts a male disguise, combing her hair back to attract female customers, but abandons the tactic upon deciding she must personally acknowledge Ika as an invader. Later, she tries pretending not to fear Ika, achieving temporary success until situations requiring physical contact, like shaking Ika's hand, cause her to flee in terror. Her fear sometimes triggers physical reactions, such as attacking Ika after an unexpected hug. At Lemon, Nagisa views colleagues Eiko and Chizuru Aizawa with skepticism for treating Ika Musume normally, which isolates her in her apprehensions. Despite this, she remains a dedicated employee, collaborating with them on restaurant operations. Across the series, her initial paralyzing fear evolves into cautious interactions, though she continues navigating her phobia. Moments like experiencing "A-Cup Angst" during her cross-dressing phase—where Chizuru suggests chest binding—highlight her vulnerability. Her character maintains this consistent arc of managing her fear while fulfilling her role.