During the curfew that keeps Class A's first‑yearers inside the UA dorm, a third‑year arrives unexpectedly—Mirio Togata. He brings along the support‑class creation, the card game Yuuei Heroes Battle, a relic of their training. As each pupil draws a deck and dives into the clash, subtle clues hint that the contest hides deeper secrets about power and destiny. Who will ultimately claim triumph?