Mysterious beings known as Disasters are a constant danger to world peace. To oppose them, an elite army unit named Saber is created, while corporations and a separate defense organization called Blade also move against the enemy. Noii, a high schooler, dreams of joining Saber and fighting the Disasters. Everything about his everyday life changes once an enigmatic girl named Motis becomes a transfer student in his class. The story centers on a fiery teenage boy, a swordswoman shrouded in mystery and an unpredictable, gloomy girl, in a world where reality and the game world can no longer be told apart and a conspiracy lies in wait. The ONA blends action, adventure, fantasy and romance.