Nonoka Komiya hasn't lived in Lake Kiriya City for seven years. Although she anticipates changes in the town, she isn't prepared for what she encounters upon her return. A colossal saucer looms over the entire city since shortly after she and her family vacated, while an unfamiliar person, Noel, is expecting her, insisting they've already met. Nonoka is bewildered, but focuses on reunifying with old acquaintances. However, buried recollections from her mother's demise begin to resurface, leaving Nonoka to wonder whether she and Noel crossed paths before. How is this linked to the saucer's appearance? To unravel the enigma, Nonoka has to collaborate with her peers and retrace the events that transpired prior to her leaving Lake Kiriya.