Kagome learns that Inuyasha wants the jewel to become a full demon . Born to a dog demon father and human mother , InuYasha is a half-dog demon who initially wants to use the power of the Sacred Shikon Jewel to become a full-fledged demon like his brother , Sesshomaru . Fifty years prior to the main era of the storyline though , Inuyasha fell in love with the priestess Kikyo , who guarded the jewel .