Infinite Stratos (IS), a Japanese exoskeleton weapon, can only be flown by women. Its strength and battle prowess are so enormous that an international treaty prohibiting its use as a military asset has been ratified. When it is discovered that 15-year-old Ichika Orimura is the only man capable of piloting an IS, he is forced to enroll in the Infinite Stratos Academy, an all-female boarding school whose graduates go on to become IS pilots. Ichika is reunited with two of his boyhood pals, Houki Shinonono and Lingyin Huang, at this training school, and befriends Cecilia Alcott, an IS representative from the United Kingdom. Ichika and the girls will need to rely on the famed pilot Chifuyu Orimura—their tough homeroom instructor and Ichika's elder sister—for guidance.