She is first seen in a cutscene at the start of the game riding with the Hero. When the Hero goes in search of food and shelter for the night, she is kidnapped. The Hero goes searching (fruitlessly) for her for several months. She eventually sends a letter to him telling him that she is being cared for. At this time, the game actually starts for real. The majority of the main quest revolves around finding her. She is the main driving force behind the bounty hunters quest. She is also used to force the bounty hunter to do things and to go to places that he wouldn't necessarily do if he had the choice. She is an unplayable character.
In the first Two Worlds game, Kira has not been seperated from her twin. This is what Gandohar plans on doing with her and is the reason why he does not kill her.