Synopsis Principles and Practices of Lovemaking ‘Sungjae’ was transferred to the Joseon Dynasty after sustaining a genital fracture during sex. Although he is somewhat satisfied with this unexpectedly sexually liberated place, he quickly decides to return to his original world. To accomplish this, he begins working on two tasks: a mission to save the king’s heir and the creation of a guide on ‘Principles and Practices of Lovemaking’ to encourage childbirth.