Infinite Stratos (IS), a weaponized exoskeleton system, has become the dominant tool of warfare and conflict. Unfortunately for the men in society, only women are able to operate Infinite Stratos... with very few exceptions. One of those exceptions is ORIMURA Ichika, an orphan raised by his older sister who is herself a famous IS pilot. When his compatibility with IS is discovered after he accidentally touches an IS at the age of 15, he's given a scholarship and enrolled in a school that specializes in training IS pilots. Which of course means an... interesting life surrounded by girls for this shy, unassuming boy.