Napping Princess: Japan, 2020, a few days before the opening of the Tokyo Olympics. Although she should be studying for her final exams, Kokone, a schoolgirl who lives in a small town with her widowed father, a mysterious and talented mechanic, falls asleep often, anywhere, anytime, entering, over and over, a dream-world where a squad of fantastic motorized contraptions fights against magic, a world close to reality where she will find out the keys of her true past.