Water is the gentlest but also the strongest of the five Elements, able to heal the most brutal injuries but also able to smash whole cities with taifun and tsunami. Water shugenja are among the Empire's most peaceful but also some of the most dangerous to enrage. Water is a source of clarity and vision, empowering divination and assisting magistrates. It is the source of life but also the inspiration of the battlefield general; the Element of motion and movement, but also the essential Element of serenity and peace.

The Book of Water is the fourth in the series of Elemental sourcebooks for the Legend of the Five Rings Role-Playing Game. Each book explores different aspects of Rokugan's world and samurai culture from the standpoint of the chosen Element. This book explores the aspects of Water, from the flowing grace of a warrior fighting with a bo staff to the ruthless tactics of merchants who exploit the flows of travel and coin.

Legend of the Five Rings (often abbreviated “L5R”) is a fictional setting that covers in detail the fantastical land of Rokugan, a nation whose culture and history is based on that of feudal Japan. The setting also briefly touches upon many of the different cultures that occupy the same world. This world is the foundation for the Legend of the Five Rings Collectible Card Game, the Legend of the Five Rings Role-Playing Game, the Clan Wars miniatures game, and a series of novels. Legend of the Five Rings was also the “featured campaign setting” of the Oriental Adventures expansion to the third edition of Dungeons & Dragons, but this book and the line of L5R material based upon it is now out of print.