Karin is the Rival of Sakura, she strives to be better then Sakura and she is known for making an entrance. Karin uses dirty tactics to win most of the time as seen in STREET FIGHTER SAKURA LEGENDS. She challenged Sakura to a hot dog eating contest, while Sakura was honestly eating every hotdog; Karin had one of her Servants under the table eating her hotdogs, Sakura's friend Hinta caught it on her camera and told her friends, when it was exposed Karin challenged Sakura to a sparring match, which turned into a full scale war, however Sakura and her friends were once again able to beat Karin, who showed some humility in her loss.
Karin was created by Masahiko Nakahira for his licensed Street Fighter manga, Sakura Ganbaru, where she proved popular enough to later be included in several of Capcom's games, starting with Street Fighter Alpha 3. This is unusual, as it's almost unheard of for a character originating in video-game licensed material to be incorporated into the license itself.