Sayaka is one of the best professional assassins in china. She was born in japan and learned the art of ninjutsu under her master Hattori Musashi.
When she was 15 her whole family was killed by the Yakuza members after her father refused to cooperate with them.
Luckily, Sayaka was away with her master training in the mountains when the incident happened. After her master learned about the tragic incident he took her to china to keep her safe.