Lena is an intelligent and strong Korean girl who is the captain of the Kendo team; she lives with her single mother, a self proclaimed 'Herb Fanatic'. When a new student, Hye-Min, transfers into her school and joins the kendo team he first mistakes her for a boy but before long they discover their love for each other. However, it is revealed that Hye-min and Lena are half-siblings. Due to the shock Lena breaks up with Hye-Min but Hye-Min's mother sends thugs after Lena. In an attempt to protect Lena, Hye-Min is badly injured and near death, and the enraged mother of Hye-Min now sends assassins who kill Lena's mother before Lena can warn her. While attempting to escape herself, Lena is stabbed by the assassins and falls into a nearby river; when she wakes up she finds herself in a strange world and she discovers that she might be its only hope!

Upon her arrival in the Scottish middle ages, she hides her sex and calls herself "Ley" and is known as a fearsome warrior. Her actions and words show the charisma of "a born leader", causing many to follow her instinctively. When she meets Maren, of the Leon tribe with the gift to only speak the truth, she is told that she was originally from the current world. A child of Jira (Zira), who became a concubine of the King of Aran, she had been stolen as a baby by the previous Queen Arianna who had become mentally unstable from the loss of her son to her daughter who later became Queen Elinor. It is still unknown which world Lena truly is from.

She's the leader of "The Five".