The Vexations of a Shut-In Vampire Princess, Vol. 7 (light novel)

Here comes the bride! After returning from her hot springs vacation, Komari is immediately thrust into another crisis when Lingzi Ailan, the princess of the Enchanted Lands, shows up at the Mulnite Imperial Palace begging for help. Apparently, the grand chancellor of the Enchanted Lands is in the process of overthrowing the current ruler, and he's forcing Lingzi to marry him to solidify his grasp on power. Sympathetic to Lingzi's plight, Komari agrees to travel to the girl's homeland to help break off her marriage. There's just one catch-the only way Komari can get the public to accept the cancelation of the wedding is to pass herself off as Lingzi's true love! But in the background of the grand chancellor's coup, something terrifying is brewing.