The Black Rabbit Count's Devoted Marriage Proposal

Emma, ​​a human, has a close friend in the beastman aristocracy, the Serpent Duke. She works as a potion maker, but the Serpent Duke has an unexpected request. It's a request for a strategy to help Lyle, a sacred unicorn beastman and royal guard knight, overcome his fear of women...!? They begin their training, but they start by holding hands and even interact like lovers! ...Don't you think their physical contact is a little too intense? A courtship love fantasy begins with a lesson with the unicorn beastman knight! (Source: Ichijinsha, translated)

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?!