Under a piercing blue sky, surrounded by crystal clear water, the sun scorched Ao Hoshizaki’s skin. Gazing at the summer scenery, it seemed as if the girl was left behind in a world that she had wandered into. At a school adrift in the distance, there lived three girls who had lost their memories. The only thing they could remember was their names. Ao, shrouded in confusion, begins to lead a strange communal life with the girls as they seek clues about a way to return to their original world.