Lillia, whose full name is Lilliane Aikashia Corazón Whittington Schultz, is the daughter of Allison Whittington and Wilhelm Schultz. She serves as the main female protagonist of the second half of the story, which takes place approximately fifteen years after the events involving her parents. Born into an aristocratic family in the eastern nation of Roxche, Lillia is raised without knowing that her father, Wil, faked his death and assumed the secret identity of Travas within the Sou Beil military. She is also kept unaware of the true identity of her childhood friend Treize, who is a prince of Ikstova, and she is generally shy about being addressed by her full given name.

Lillia is depicted as a young, adventurous, and confident individual with a strong sense of courage and determination. She is naturally curious and enjoys seeking out new experiences, often displaying a quick-thinking and fearless attitude when faced with danger. Beneath her spirited exterior, she is deeply caring and compassionate, possessing a strong protective instinct toward those she loves. Her loyalty to her friends and family is unwavering, and she often puts the well-being of others ahead of her own. Her motivations are shaped by the legacy of her parents' quest to end the long-standing war between the eastern and western regions. She strives to carry forward that hope, working to thaw the divisions between the torn nations and foster unity in a world long plagued by conflict.

Her role in the story begins during her summer vacation from school, when she embarks on a series of adventures alongside Treize. Together, they become entangled in political intrigue, assassination attempts, and war-ending missions, reflecting the same pattern of high-stakes adventure that defined her parents' earlier journeys. Her key relationships include Treize, her loyal childhood companion who harbors romantic feelings for her but struggles to reveal his royal status; her mother Allison, a former pilot whose adventurous spirit Lillia has inherited; and her father Wil, whom she believes to be deceased, though he secretly watches over her from the shadows. Through these relationships, Lillia grows from a spirited schoolgirl into a capable and determined young woman, learning to navigate complex political realities and her own emotions.

Notable abilities include her skill as a pilot, a talent she inherits from her mother, as well as competence in hand-to-hand combat. She is also resourceful and quick on her feet, able to adapt to dangerous situations through a combination of physical ability and clever thinking. Her development throughout the series sees her mature into a figure who actively works toward peace, embodying the hope that her parents began.