Hayate the Combat Butler Vol. 3 (manga)
As if dealing with his mistress Nagi's outlandish demands weren't taxing enough, poor (yet perennially) hardworking Hayate has to suffer the ignominy of being challenged to a duel by Nagi's fiancé Wataru Tachibana. With his saber at the ready, Hayate is prepared to defend himself...but is there any logical reason why he's even fighting a duel in the first place? Shouldn't the simple act of keeping the Sanzenin household spic-and-span be enough?