Typical anime plot: normal boy/girl gain SUPAR HAPPY FUN-TIME POWERS and they must save the world. If they are a guy, they are emo because they were neglected as a child or something; if they are girls they are complete bimbos. Regardless of whether they are guys or girls, all their best friends are absolute retards who serve as the comic relief/cutesy relief.
The villain is always set up as some ancient evil who blah blah blah. Surprise twist: the villain is somehow related to the protagonist. Usually their sibling/lover/father/best friend they had a falling out with.