Sakura is a ten-year-old girl who lives in the fictional town of Tomoeda in Japan, near Tokyo where she attends Tomoeda Elementary School. At the beginning of April, shortly after her birthday, Sakura finds a mysterious old magic book called The Clow in her father’s study which contains a deck of 19 (52 in the anime) powerful magical cards. Upon touching it, Sakura awakens one of the card’s guardians, Cerberus, who was sleeping on the front cover guarding the Clow Cards. After awakening, Cerberus emerges from the book and admits to letting the cards escape while he slept. Realizing Sakura’s magical potential, he cunningly tricks her into becoming the "Cardcaptor" and thus becoming duty-bound to reclaim the missing cards under her control. In addition, the ceremony secretly marked Sakura as Cerberus's chosen candidate to become the next master of the Clow Cards and their guardians.
In the anime, the series presents a slightly altered chain of events. On the afternoon after her first day of fourth grade, Sakura hears a mysterious sound coming from her father's library in the basement. She arms herself with her cheerleading baton and nervously goes downstairs. On a table she discovers the false book The Clow with all of its cards still inside. After opening The Clow, Sakura picks up the top card and reads its name aloud which activates it, summoning a powerful wind which blows the remaining cards away and scatters them across the town. After all the cards but "Windy" have been blown away, Cerberus emerges and forces her to undergo the ceremony to retrieve them. This was most likely added to not only give Cerberus a more justifiable reason to send Sakura on her mission, but also to give her an easier time at completing it, as she now begins her adventure with one of the cards, Windy, already under her control, as opposed to starting with no cards at all as in the original manga.
Sakura is an extremely energetic and cheerful character. She is very athletic, being a member of her school's cheerleading squad and excellent at track-and-field activities. Her "invincible spell", "I'm sure I'll be all right.", has carried her through innumerable trials and obstacles as she masters her magical skills. She often comes across as naïve, clumsy, and clueless, but she has her perceptive moments on occasion.
Sakura's optimistic and trustworthy character allows her to be friendly with everybody, and the entire series focuses on the friendships she creates with people, whether strangers, loose acquaintances, or rivals. In fact, her personality is a dominating factor in her relationships, especially with Syaoran.