Juujin Taichou no (Kari) Konyaku Jijou Totsuzen desu ga, Ookami Taichou no Kari Fiancée ni Narimashita

A member of the beastkin nobility and the heir to the Bearwolf Marquis, Leold, suddenly bites Katie on the shoulder, branding her with a "Mark of Proposal". Katie, who was crossdressed at the time, is mistaken as a male and dragged into being his fiancée for a few years until the mark disappears... But the two have the worst relationship...! What is this? A form of courtship?! Source: MU