What to read after Into the Fire?

In this exciting new chapter book series from New York Times-bestselling author Tracey West, a ninja-in-training must use skills he doesn't know he has to defeat a deadly enemy.
Hiro and his family have successfully prevented evil warlord Fujita from getting his hands on the Amulet of the Moon. But they must also protect the Amulet of the Sun from the dark ninja's grasp. Fujita is more determined than ever to wield the power of both amulets. And with a gang of stealthy ninjas on the attack, Hiro knows it will not be easy to get to the sacred talisman before Fujita does. He'll have to use all of his ninja skills--and his new-found monkey spirit--to help defeat Fujita once and for all. Even when it means descending into the depths of a deadly volcano...