Something Seems Off About My Master

A female master and her young disciple. A heroine who puts on a solemn act while swearing, paired with a tsundere, pure-hearted cat-eared boy. Even the side characters are snarky. This should count as a cute story, right? The heroine's motto: A second senior sister who can't do the job of the eldest senior brother can't become sect leader. (The author has been watching too much Gintama lately.)