The Irregular at Magic High School Novel Volume 21 is written by Tsutomu Satou with illustrations by Kana Ishida.

It's March of 2097 when Synchroliner Fusion is deployed in South America, and the worldwide upheaval that rose up in its wake has finally reached Japan. The following month, Tatsuya and Miyuki receive a message from the head of the Juumonji clan, Katsuto. They are both formally invited to a conference of the Eighteen Support Clans over rising hostilities directed at the group, ensuring yet more trouble in Tatsuya's future.