The Asterisk War, Vol. 4 (manga) — Yuu Miyazaki

Kirin Toudou is the top-ranked student at Seidoukan Academy despite her young age, but there's one enemy she cannot face--her controlling, abusive uncle! After witnessing the man's cruelty toward his niece, Ayato steps in to help, but he soon finds himself facing her in a duel! With the Festa just around the corner, can he really afford to reveal his dueling style in front of the whole school, or will he have to accept defeat?