This is very important. The novels Yi Pin Dan Xian and Dao Men Fa were written by the author Babaofan, and the author is the same person, so they are related. "Yipin Danxian" tells the story of how a protagonist who passed through a period similar to the Spring and Autumn Period and the Warring States Period embarked on the road of immortality from an assassin whose martial arts were completely abolished. The Law of Doors is a novel about chivalry, which tells the story of the protagonist practicing in a world controlled by doors.