I'm Only A Substitute Consort, but the Emperor Won't Let Me Leave

The daughter of a wealthy merchant, Sai Reiran, was chosen to become the Emperor's newest consort. however, on the trip to the Imperial Capital, she runs away with the son of another merchant! In order to fulfill the emperor's orders, and keep their heads, the family orders Reiran's cousin, Shuran, to take her place instead! They tell her to just...