The Yoka Empire, led by its supreme commander Tadaomi Oka, and the enigmatic military state of Walmgraf, commanded by Gustav Heydrich. An alliance is forged between the two nations, and their shared ambition of "unifying the world" begins to feel within reach. On the day of the Spirit Cherry Blossom Festival, held once every ten years in the Yoka Empire, a mysterious demon appears amid the bustling capital.