Hayato Kisaragi wants to become a Slayer, one of the few pilots who can operate a Hundred combat suit against the alien Savages threatening Earth, and enrolls at Little Garden, a military academy built on a battleship. His transfer immediately draws attention from classmates Emile Crossfode and Claire Harvey, pulling him into both training drills and the personal entanglements that come with it. This manga adapts the first volumes of Jun Misaki's light novel series.