Nagisa is a mysterious girl who appears on a small island during a summer vacation trip taken by Nube and his class in the movie Jigoku Sensei Nube: Kyōfu no Natsu Yasumi! Ayashi no Umi no Densetsu. She is encountered on the beach and invites the group to go into the sea, displaying a strange charm that quickly captures the attention of the student Hiroshi. Shortly after her appearance, several of the other characters, including Kyoko and Ritsuko-sensei, are attacked under unusual circumstances, raising questions about her true identity. The island is the setting of a local legend about a creature known as the sea spider, a monster that, once it reaches two hundred years of age, devours human sacrifices. Nagisa’s role in the story is central to the mystery surrounding these events: she serves as the initial lure that draws the protagonists into the water, and her connection to the sea spider legend becomes the focal point of the plot. Her background is not explicitly detailed in the film, and her motivations are tied to the supernatural threat of the sea spider, suggesting that she may be a manifestation or agent of that creature. She has no known special abilities beyond the alluring presence that influences those she meets, and she does not undergo personal development within the span of the story. Her key relationship is with Hiroshi, whom she first attracts, and through him she becomes intertwined with the group’s investigation of the legend. Overall, Nagisa functions as the enigmatic figure whose appearance triggers the conflict between the human characters and the island’s ancient, malevolent force.