Karin is a sensor-type ninja with the ability to heal an ally by letting them bite her and suck her chakra. Karin is an ill mannered young woman with a fiery temper.
Karin was the warden at one of Orochimaru's hideouts until Uchiha Sasuke killed Orochimaru. Sasuke and Suigetsu came to the hideout and set the prisoners that Orochimaru had been experimenting on free. Sasuke and Suigetsu approached Karin about joining their team but she declined until Suigetsu left the room. When Karin was alone with Sasuke it was revealed that she had a crush on Sasuke from the day she met him and agreed to join the team called Hebi.