Yuuki Wakasa is a typical fifth-grade student at Kamishiro Elementary School, except for one flaw: her mischievous younger siblings drive her nuts. One day, a small red bean called a magatama falls from the sky and Yuuki becomes fearful at first. However, throwing the stone away is considered a bad omen, so she decides to keep it. That night, she sees a mysterious woman through a magical mirror called Shinjyukyou.
The woman warns Yuuki that their world is in grave danger due to Amaterasu, the sun goddess, going missing. Strange and dangerous weather patterns have emerged as a result of this sudden absence. Yuuki is chosen to be the "Horizon Girl" and is entrusted with finding the other four magatama bearers, known as Amatsukami, so that they can come together and save Amaterasu before the sun disappears completely from both the physical and spiritual world. They must travel to the dream world together to confront this daunting challenge.
