Sakura Kinomoto is just your typical Japanese 4th grade schoolgirl. That is, until she finds a book in her father's library and accidentally breaks the seal. The book contains a set of cards. Upon reading "Windy" on one of the cards, a great wind is conjured and blows all of the cards out of the book, and they disappear out of sight. A tiny yellow creature appears out of the book. He introduces himself as "Keroberos, guardian of the seal". After freaking out that all but one of the cards (Windy) are gone, he names Sakura a "cardcaptor" and responsible for getting all of the cards back, because the cards were magical "clow cards", capable of causing mayhem upon the earth. And, this is where Sakura's adventures begin!