10 years after the disaster, Princess Sania of Millmana is leading her city in rebuilding the world. She encounters a young man named Halt, who serves in the vigilante corps of Millmana. Halt encounters the mysterious girl Mizuha on his journey to Gertrude. He brings Mizuha to Millmana so she can recover from her wounds.

In the game, the player can control one of the heroes of the series: Halt, Mizuha, Kukuru, or Lieza. Each hero has their own set of skills that can be cast on the enemy. Players can also use gacha to collect various heroes from the anime series.

The story of the game begins with the main character Halt, who is a young man who is brave and kind-hearted. He encounters the mysterious girl Mizuha on his journey to Gertrude.