Mitsuba Sousuke is from a small but influential family whom rule a small kingdom, and Kou Minamoto is from a very large powerful clan and kingdom of exorcists. Any marriage into the Minamoto clan is a large power boost. Ever since Kou was a child, he was tossed around from proposal to proposal not as much as his brother or his sister (even tho is sister is much younger than him) but still. A marriage to him would've boosted any country or kingdom. Since Kou was not the first born, he would not be king but he might rule a smaller kingdom from the lands his families own, maybe even be a military officer? Who knows. One day Mitsuba's uncle (The king of said small kingdom) manages to sway Kou father into a deal, the deal being Mitsuba and Kou being married. How will they handle this? will they immediately divorce? Who knows.