Akashic Records of Bastard Magic Instructor Vol. 7 (manga)

FOR YOUR HAND IN MARRIAGE

An old childhood friend of Sistine's shows up at the university and lays down a bombshell: he's her long-estranged fiancé! Leos intends to make good on their engagement, and what's more, he wants her to quit her studies immediately and leave her dreams behind. But if there's one thing Glenn can't stand, it's somebody pushing one of his students around. Before anyone can stop him, he challenges Leos to a duel over Sistine's hand in marriage!