Fourth Tokyo, the Japanese colony built on Mars, is where test pilot Iris Shirasaki and mechanic Mizuki Sera train under the aerospace program run by Kaito Sera, Mizuki's own brother. A transfer student named Nagisa Kiryuu arrives with an agenda that starts to unravel the program from the inside, forcing Iris and Mizuki to reckon with how much of their school is really about the students at all. This light novel is a separate adaptation of the same Classroom☆Crisis TV anime that the manga also adapts.