Karin is a schoolgirl from a wealthy family who was first arrogant towards the people around her. This lousy trait was reflected in her behavior and made it difficult to make friends. After Karin grew up a little, she reconsidered her attitude towards people.
The initial, negative period in Karin's life also includes her conflict with her father, who sought to raise his daughter "like a son." He instilled in her a sense of purpose and desire to win consistently and everywhere. Ironically, Karin took the family company away from her father in an aggressive takeover.
Karin has a best friend, Sakura, with whom they competed strongly at first. Growing up, Karin began to realize that striving to win always and everywhere is a terrible desire. She decided to learn to enjoy the fights themselves, not their result. Karin has also become more polite towards people, although she retains a little indulgence towards others.
Her friendship with Sakura is confirmed by this time, although their rivalry is very much present still.