Engineered by Japan, the exoskeleton weapon known as Infinite Stratos (IS) can be piloted exclusively by women. Its immense power and combat capabilities have led to an international treaty banning its use as a military asset. Upon the discovery that 15-year-old Ichika Orimura is the only male capable of operating an IS, he is forcibly enrolled in the Infinite Stratos Academy. This all-female boarding school trains students to become IS pilots. There, Ichika reunites with two childhood friends, Houki Shinonono and Lingyin Huang, and befriends Cecilia Alcott, the IS representative from the United Kingdom. Under the guidance of the legendary pilot Chifuyu Orimura—their strict homeroom teacher and Ichika's older sister—Ichika and the girls must utilize all available resources to defend themselves and their academy against the dangers that emerge during their thrilling school life.