Ten years have passed since the events of Mahou Shoujo Lyrical Nanoha A's. Nanoha, Fate, Hayate, and their comrades have joined the Time-Space Administration Bureau in various roles. Nanoha trains soldiers in combat, Fate is assigned to investigate special cases, and Hayate is now a commanding officer. The team reunites to prevent dimensional threats, and they are joined by new characters including Subaru, Teana, Caro, and Erio. Get ready, the mission is about to begin!