Hilo and his friends learn more about Hilo's past while they battle robots that were buried underground on Earth a thousand years ago.

"The boys of Huaxia dream of pairing up with girls to pilot Chrysalises, giant transforming robots that can battle the aliens that lurk beyond the Great Wall of China...When 18-year-old Zetian offers herself up as a concubine-pilot, it's to assassinate the ace male pilot responsible for her sister's death. But when she gets her vengeance, it becomes clear that she is an Iron Widow, a rare kind of female pilot who can sacrifice males to power up Chrysalises...