Ten years after the events of *Mahou Shoujo Lyrical Nanoha A's*, Nanoha, Fate, Hayate, and the rest of the team are now full‑time officers at the Time‑Space Administration Bureau. Nanoha serves as a combat instructor, Fate works as a special investigator, and Hayate holds the rank of commanding officer. Together, they must unite once again to defend the dimensions. The story also introduces new characters: Subaru, Teana, Caro, and Erio.