Question: the irregular at magic high school are tatsuya and miyuki related

Answer: Yes, The story takes place in an alternate history where magic exists and is polished through modern technology. It follows Tatsuya and Miyuki Shiba, siblings who enroll into First High magic high school. While keeping their connections to the infamous Yotsuba clan secret, they attempt to live their daily life in peace where Tatsuya is shunned for his apparent ineptness and Miyuki is validated for her magical abilities.