In the 298th year of the divine era, young schoolgirls Washio Sumi, Nogi Sonoko, and Minowa Gin are given a crucial assignment. They must transform into heroes to combat Vertex, an enigmatic foe threatening Shinju-sama, the sacred tree safeguarding Shikoku, the last livable region on Earth. Unbeknownst to them, this battle will demand sacrifices far beyond their expectations.