Pinkie Pie has a new hobby that she absolutely loves - playing the Zenithrash; when her friends discourage her from playing due to her lack of skill, it causes a series of events leading to Pinkie Pie possibly leaving Ponyville forever.
"Get your muzzle out of those books and make some friends!" That's what Princess Celestia tells Twilight Sparkle. She may be the smartest unicorn in Equestria, but Twilight Sparkle gets an "incomplete" in friendship. There's more to life than learning magic, after all - so she goes to Ponyville on a mission to make friends. There she meets five special ponies who take her on exciting adventures and teach her the most powerful magic of all... the magic of friendship!