In volume 5, InuYasha's secret weakness--during the time of the new moon--is revealed when he must fight a Spider-head demon to save a young orphan girl.
Then, InuYasha and Kagome must pursue the Ogress Urasue, who has stolen the bones of Kikyo, the priestess who trapped InuYasha in a magical slumber for fifty years. Urasue raises the body of Kikyo, who is still furious at InuYasha...