Kion and Rani: The Demon Inside (Book 2 of 2)
Kion had been freed from evil. He no longer hurt others. But, evil never actually left. At sunset one day, when Sawa and Raja were about 15, something corrupted Raja, and he attacked....Read to find out more! You should read the first book. it is called the same thing, just labeled at 1 of 2.