Grass for His Pillow by Lian Hearn

The journey continues... The sequel to Across the Nightingale Floor follows the separate fates of young lovers, Otori Takeo and Shirakawa Kaede, as they fight for survival in a violent time of war, famine and treacherous alliances. Takeo has pledged his life to the secret Tribe. His supernatural skills of invisibility and acute hearing make him their most deadly assassin. He must deny the spiritual vows of his upbringing, his birthright of Otori wealth, land and power - and his love for Kaede. If he does not serve the Tribe, they will kill him.