Help each other and strive to become a complete citizen. In the past, Kobato had a bitter experience because he liked to engage in reasoning activities that he called "using his brain", which made him determined to become a cautious citizen. He and his classmate Osanagi, who had the same aspirations, formed a close "reciprocal" relationship of mutual help and prepared to welcome a new high school life as citizens. But for some reason, incredible events and disasters continue to befall their campus life. Can Kobato and Osanagi get the stable life of citizens they dream of?