Crimson Prince, Volume 16 (Crimson Prince #82-87)

The story of Koujirou's parents continues... Medicine-maker Margaret finds herself becoming more and more involved in the affairs of another world after creating a special remedy for a man named Sentarou. The pair is slowly falling in love, too, but there's one major problem: Sentarou is a demon, and Margaret is a human. Are they doomed to be star-crossed lovers, or can they find a happy ending?