“Eria,” “Hiita,” “Wynn,” and “Aussa” are each striving to become a full-fledged Spirit Charmer alongside their familiars. One day, Eria discovers a grimoire in the archives, which describes the grand Spiritual Art, "Ichirin.” The four attempt to perform it, but the imbalance of their spiritual power causes the ritual to fail. Disheartened, they follow the mysterious letters that appeared in the book, leading them to an ancient altar hidden deep within the ruins. There, the door to a mysterious trial is about to open...