After ten year old Sakura accidentally unleashes a set of magical cards from their book, the Clow, it falls upon her to find them and seal them. To help her, she has the guardian of the Clow, Cerberus (Kero) who usually takes the form of a stuffed bear, and her best friend, Tomoyo, films everything (while also providing Sakura with a costume for each adventure). Syaoran Li (Li-kun), a descendant of Clow Reed, the man who created the cards, shows up to fight her claim on them. In the end, who will seal the cards and will simply sealing them be enough?
Kero-chan (Cerberus): While he was put in charge of guarding the book of the Clow and selecting a new master for the cards, he fell asleep on the job, thus allowing Sakura to open it. So he decides that she shall be the new master. Kero is a bossy, demanding character who's a bit of an ego maniac. He spends a lot of his time playing video games and eating sweets. Still, he knows his stuff when it comes to magic and is a big help to Sakura.
Tomoyo: Tomoyo is Sakura's best friend and cousin. Her mother owns a very popular toy company, so she has a lot of money that she willingly uses to help Sakura out (though mostly just by making her outfits). She often talks very formally and acts more mature than her classmates. She's a very kindhearted girl, who just wants to be Sakura's friend and help her find love.
Li-kun: Li can come across as harsh at first, and thinks that he and not Sakura should become the master of the Clow since he's descendant of Clow Reed. Eventually he becomes friends with Sakura and cares deeply for him. He can be awkward and uncertain of how to deal with and show his feelings.
I originally watched the fansubs of all 70 episodes of this anime and loved it. I then borrowed the manga from some friends and I found that it was equally as enjoyable as the anime. There were differences (more cards in the anime and an extra character) but both were good. I absolutly adore this story. Sakura is a very likeable character and Li-kun is my favorite character in all of manga. Clamp does a wonderful job of weaving a story of adventure and growth and young love around Sakura and her adventures to get the cards. If you enjoy a magical girl story or think you might, then Cardcaptor Sakura is a must read.