The Irregular at Magic High School, Vol. 2 (light novel) - Enrollment Arc, Part II

Tatsuya and Miyuki Shiba are brother and sister, but they share a bond that transcends mere blood relation. Despite being siblings who attend the same school, their lot in life couldn't be more different. Miyuki's a Bloom, on of the elite students of the school, while Tatsuya's a Weed, with low expectations and even less respect. But having skillfully diffused a tense situation, Tatsuya finds himself recruited by the school's disciplinary committee, and soon discovers there's more to Magic High School than he realized...