From the introduction:
In the Palace of the Emerald Champion is a bonus adventure for the Legend of the Five Rings Roleplaying Beginner Game. It is designed to follow the events of The Topaz Championship, the adventure included in the Beginner Game.
During the events of The Topaz Championship, the Player Characters (PCs) underwent their gempuku, or coming-of-age ceremony, which consisted of a series of contests concerning athletic skills, martial prowess, and knowledge of Rokugan’s history and culture. While there, they encountered a mysterious ghost and uncovered a plot to disrupt the tournament. Their heroic actions attracted the notice of the Ruby Champion, who recommended them to become Emerald Magistrates.
Now it is time for the PCs, who have become full samurai, to go to the palace of the Emerald Champion to begin their training and assume their new duties to the Emperor. The castle is filled with intrigue and danger, however, and their training may be the least of their worries.