Mahouka Koukou no Rettousei: Yoru no Tobari ni Yami wa Hirameku

魔法科高校の劣等生 夜の帳に闇は閃く

The story of the spinoff novel follows the Kuroba twins, who are sworn to protect Tatsuya Shiba. They face a new threat when an enemy from a foreign mafia sets eyes on Tatsuya. (Source: Anime News Network, edited)