Across the Nightingale Floor (Tales of the Otori - Book One)

This is a fast-paced fantasy with Japanese influences. Lord Shigeru rescues Takeo from certain death when the villainous Iida destroys Takeo's village and kills the members of the Hidden that live there. Takeo pledges his loyalty to Lord Shigeru, who adopts him. The mysterious Kenji appears and informs Takeo that he actually belongs to the Tribe, who will at some point lay claim to him. Takeo lives with Shigeru, but Kenji begins to train him in the skills of the Tribe including assassination.