Heaven's Net is Wide by Lian Hearn

Heaven's Net Is Wide is the new first volume of the now complete Tales of the Otori- prequel to Across the Nightingale Floor, the book that first introduced Hearn's mythical, medieval Japanese world. This is the story of Lord Otori Shigeru-who has presided over the entire series as a sort of spiritual warrior-godfather-the man who saved Takeo and raised him as his own and heir to the Otori clan. This sweeping novel expands on what has been only hinted at before: Shigeru's training in the ways of the warrior and feudal lord, his relationship with the Tribe of mysteriously powerful assassins, the battles that tested his skills and talents, and his fateful meeting with Lady Maruyama.