The Irregular At Magic High School: Visitor Arc

"Three years ago, he had the same posture. Three years ago, he had stood behind Miyuki. Yes.... Compared to three years ago, it had changed." Set 3 years prior to the present time, Tsuioku Hen tells the events that would change Miyuki's world drastically, as well as the events that led Tatsuya to become what he is now.

Mahouka Koukou no Rettousei: Double Seven Hen (魔法科高校の劣等生 ダブルセブン編) is the manga adaption of the 'Double Seven Arc' from the 12th light novel.

The year is 2095. Magic has been tamed as another form of technology, and the practice of magic is now a rigorous discipline. Brother and sister Tatsuya and Miyuki Shiba are just about to start their first year at the renowned First Magic High School of Japan. But the school's ironclad rules mean that the brilliant Miyuki enters the prestigious Course 1, while her older brother, Tatsuya, is relegated to Course 2--and that's just the beginning of their troubles! 

(Source: Yen Press)