High school students Mayumi and Kiwako are relishing their summer vacation at the beach; however, when Mayumi discovers a presumably lost camera while scuba diving, she cannot help but feel an insatiable curiosity. Upon developing the camera's film, she is shocked to find herself photographed alongside an unknown man. Enlisting the help of Kiwako's older brother, the three find out something even more troubling: the camera model has yet to be released. In turn, Mayumi becomes obsessed with discovering the origin of the peculiar camera and its mysterious photograph.