Sakura Kinomoto, an ordinary ten-year-old girl in the fourth grade at Tomoeda Elementary, comes home one day after school to hear strange noises coming from her father's basement library. Unable to ignore the noises, she arms herself with her cheerleading baton and with all the courage she can gather, heads down the steps into the dark basement.
Cautiously, she moves along each row of bookcases finding nothing until she reaches the last row of bookcases. Expecting to find someone or something there, she jumps out in an attempt to scare them but it is empty; there is nothing there except for a glowing book which captures Sakura's attention. Intrigued, Sakura walks over to the bookcase and takes the glowing book off the shelf. Entitled 'The Clow', Sakura opens the red-and-gold book to find a deck of cards. She takes the first card out the book and reads the text written on the bottom - "The Windy." Upon uttering these words, a magical circle appears beneath her feet along with a big gust of wind which sends all the cards soaring into the outside world.
After the wind stops, Sakura falls to her knees and drops the book on the ground. All the cards have escaped except for the one Sakura still holds in her hand. Just then, 'The Clow' begins to glow once more and something resembling a stuffed toy begins to emerge from the book. Sakura is alarmed by this creature who claims to be Kerberos, the guardian beast of the seal. After introducing himself, Kerberos notices that 'The Clow' is empty; no cards remain except for The Windy in Sakura's hand. Wondering where all the cards have gone, Sakura tells him of what just happened. Both laugh for a moment before the seriousness of the situation becomes apparent.
The cards in the book that escaped are in fact Clow Cards - powerful magical cards created by sorcerer Clow Reed that if left unsealed, could cause a disaster to befall this world. In order to prevent this from happening, a reluctant Sakura becomes Cardcaptor Sakura, whose task is to recapture each card one by one using her intelligence and magical ability.
Sakura is not alone in her quest for the Clow Cards however. She is assisted by both Kerberos and her best friend, ten-year-old Tomoyo Daidouji. Kerberos, who Sakura and Tomoyo nicknamed Kero-chan, provides Sakura with the guidance she needs in order to successfully recapture the cards while Tomoyo provides Sakura with not only advice and support but also helpful items which make capturing cards easier as well as battle costumes designed and created by her.
Gradually, Sakura is able to recapture the Clow Cards one by one and in the process, she learns not only about the cards but herself and her magical ability: she grows in strength as well as a person, gaining confidence and learning not to doubt her ability to accomplish certain tasks such as capturing cards.
Before long however, Sakura is facing a rival not only for the Clow Cards but the heart of her love, Yukito, in the form of a boy named Syaoran Li, an exchange student from Hong Kong. Syaoran Li is a descendant of Clow Reed, the creator of the Clow Cards, and believes it is his right to have possession of the Clow Cards. He demands that Sakura hands over the cards she has already captured, but when she refuses to, Syaoran becomes forceful and attempts to take the cards. Before things become out of control however, Touya, Sakura's older brother, comes to her rescue.
Syaoran is severe, cold and seems to have a strong dislike of Sakura. He also proves to be a strong rival for the Clow Cards when Sakura, much to her disappointment, is forced to lose some of the Clow Cards to Syaoran. Eventually however, as more Clow Cards appear, Syaoran's attitude towards Sakura changes slightly and the two are no longer rivals for the cards; they begin to develop a friendship.
It is not long before another rival appears however. This time, it is in the form of Meiling Li, another exchange student from Hong Kong who is Syaoran's cousin and fiancee. Although she does not prove to be a real rival for the cards as she posses no magical ability, Meiling is incredibly athletic and gifted at martial arts.
Meiling, just as Syaoran did, seems to have a strong dislike for Sakura. However, this stems from jealousy and insecurity as she feels Sakura is her rival for Syaoran's heart. Meiling tries her best to impress Syaoran, even attempting to take on the Fight Card alone, but he takes little to no notice and often feels she is just in the way. However, this does not deter Meiling; she continues to fight for Syaoran's affection even if he does not return her feelings.
Soon however, the situation between the three improves and Sakura, Syaoran and Meiling along with Tomoyo and Kero-chan work together to capture the remaining Clow Cards, although not without the not-so-occassional argument between Kero-chan and Syaoran!
The first season of Cardcaptor Sakura consists of 35 episodes, making up part one of the Clow Card arc of the story. Each episode was preceded by the opening theme, Catch You Catch Me performed by GUMI and followed by the ending theme Groovy performed by Koumi Hirose.