This is book 1 of the Young Samurai series.
The year is 1611, Jack Fletcher is a young English boy who is sailing toward the Japans with his father, the pilot, and a crew on a trade ship. Until now, only the Portuguese have known the route but Jack's father claims to have knowledge of the way in his rutter, a navigational diary of sorts that apparently others would kill for.
After the ship becomes damaged and waylaid in a bay off the coast, it is attacked by ninja. The next morning, Jack finds himself orphaned and shipwrecked in Japan. He knows nothing of the language or customs save one thing, if you see a samurai, bow low. This bit of knowledge saves him in a tense situation. After that, he tries to begin learning everyday words to help him communicate. Soon after, the leader of the Samurai adopts him into his family and with the help of a Portuguese priest, Jack learns the language of his captors turned saviors.
This book talks about karate and the training of the samurai but also covers the values of this training. Loyalty, honesty, courage are all inspected in different ways in this book. While Jack never forgets the little sister he left behind in England and wonders about her fate, he stays focused on the task at hand. The task placed before him is to complete samurai training at a school in Kyoto. He also must figure out who has hired the ninja assassin to kill him and steal his father's rutter.