Kazumi learns that she is the 13th synthetic magical girl created by the Pleiades star cluster. Faced with this shocking truth, she finds herself targeted for her life by Satomi's magic. Although Kazumi manages to escape alone, she is determined to confront the members of Pleiades. At the same time, a girl is seen with a dark smile... This is the highly popular original spin-off story, now in its fourth installment!