The Warrior's Path (Sisters of the Sword) by Snow, Maya (2009) Paperback

Kai Provence, Japan. 1216. Hana and Kimi are delighted when their heroic uncle, Hidehira, arrives at their palace, along with his dashing army of Samurai soldiers. He is their father's right hand man, a guardian and protector who helps him govern the land on behalf of the Shogun. So when Hidehira and his army slaughter their father and elder brothers, the girls are stunned. As the palace burns around them and servants are put to the sword, Hana and Kimi have to fight for their very survival. They manage to escape - just - but are separated from their mother and youngest brother. Now the whole country is searching for them - and anyone who helps them will be put to death. The girls must disguise themselves and find somewhere to hide out. And their solution is so daring - and so obvious - that it will either work brilliantly or end in their deaths. Betrayal, heroism and avenging their father's murder will hover at the edge of every thing the sisters do from now on...