The Irregular at Magic High School - The Master Clans Conference Arc

At the Yotsuba New Year's gathering, Miyuki was names as the successor whilst Tatsuya was named her fiancé. Tatsuya and Miyuki's non-sibling relationship and engagement are now public knowledge. Among the shocked students the most shocked are those that knew the siblings.
Meanwhile, the Ten Master Clans selection meeting, followed by magicians all over the world, is due to take place at a hotel in Hakone.

Adaptation of the original novel's volumes 17-19.