The choice is simple: the prince will travel to his enemy's kingdom and share the king’s bed, or else the war continues. But Rin will not lower himself to be a whore, so he demands a contract requiring the king to be faithful. In return, the prince will risk his life by giving the king a child.Where Rin expected nothing more than a business arrangement, he receives affection, yet the more surprising realization is the willingness of his own heart to return the same. But even his king cannot save Rin from those who wish him harm, and their joining might be over before it can fully bloom.