In his latest adventure, Inuyasha: Secrets of the Divine Jewel, the title character and his massive sword team up with a new protagonist, a high school girl. Sound familiar? If not, you don't know much about Inuyasha, my friend. He's a half-demon dog-child (peep the ears) that follows around a schoolgirl named Kagome who freed him from imprisonment and has a knack for getting into trouble. He yells her name a lot and they travel around with/get into fights with all sorts of wacky, quasi-mythical types. And there you have it.
Enter Janis, Kagome's new school friend who follows her down the time-travel-to-feudal-Japan well, in the process absorbing a fragment of the Shikon jewel. Any time someone absorbs a jewel, you know there are going to be magical repercussions, and the quest to figure out what exactly those are drives the story.
When Janis, Kagome, Inuyasha and a few other familiar characters set off, everyone except Janis starts out with all the formidable powers they have in the series. As a result there's no contrived need to unlock things you already know about. Janis is really the only one who evolves in this way, growing stronger and discovering her new jewel-endowed powers.