On an early summer’s day, just before the rainy season is about to begin, you discover a mysterious, indecipherable book, as well as a man named Dorico — the self-proclaimed God of the land you are in. And like that, the story begins—— The stage is set in Heisei 30 (2018), where a portion of Japan’s culture was lost due to World War 2.5. With many of its 「books」 damaged during the war, you, the heroine, become the ‘librarian’ of the Gunjou Island Library, the ruins of a library built upon a cobalt blue sea. It is then, when you discover a mystery book that surpasses the laws of time.