The game is based on the manga Cardcaptor Sakura by the manga artist group CLAMP, and is a Japan only release.
Sakura Kinomoto is (or maybe was) an ordinary 10-year old girl. She went to school, joined a cheerleading club, and loved sports. She lived with her brother and father in a nice house in the Tokyo suburb of Tomoeda, and was pretty led a normal life.
Then one day, while home alone, she found a mysterious book in her father's study, called "CLOW". What she didn't realize was that book would change her life...she opened it and released a powerful deck of magic cards; alive with souls and unspeakable powers. The cards scattered across Tokyo, and the Guardian Beast of the Seal, Kerberos, has put her in charge of gathering the cards back up.
The birth of a Cardcaptor, Sakura Kinomoto! Now Sakura must locate all of the cards, aided by Kerberos, her best friend Tomoyo Daidouji, and a mysterious boy from Hong Kong named Shaoran Li. Together, the four must find all the cards before chaos is unleashed on the world!
Cardcaptor Sakura is a very simple adventure game. Typically, the player navigates Sakura on a very brief and linear path, until a mini-game and/or an anime-style cutscene takes place. The mini-games are quite simple as well, usually involving timed sequences and patterns.
The events in this game cover up to Volume 6 of the manga series, and up to the end of the 2nd season in the TV series. The Sakura Card story (the 3rd TV series season and from Volume 7 onward in the manga) aren't covered.