Legend of the Five Rings Core Rulebook - Rules of Play says:

At 336 pages, The Legend of the Five Rings Roleplaying Core Rulebook allows gamemasters and players to enter the world of Rokugan like never before. The Core Rulebook is the next step for players after the Legend of the Five Rings Roleplaying Beginner Box, and offers players new ways to customize their characters and craft their own adventures in the Emerald Empire.