Lydia Gurtland is a student athlete competing in the Daiundoukai tournament for the title of Cosmo Beauty. She possesses waist-length blonde hair and blue eyes, often dressed in athletic wear including a competition leotard.

She is the descendant of Jessie Gurtland, a celebrated athlete from the original Cosmic Beauty competitions a century prior. Lydia belongs to the influential Gurtland family, whose weapons manufacturing corporation supplies advanced arms to factions engaged in a lunar civil war. This conflict involves the Beginners, a pacifist moon-based religious group who abandoned non-violence for armed struggle.

Her family's role in the war fuels significant tension with fellow competitor Yana Christopher, a Beginner who holds Lydia accountable for the violence against her people. Initially displaying arrogance reflective of her privilege, Lydia gradually develops a sense of responsibility regarding the lunar conflict. Her character arc involves confronting the consequences of her family's arms trade and striving to end the bloodshed caused by their weapons. While motivated to stop the carnage linked to her family, she struggles to express her true feelings, particularly to Yana.

Lydia trains alongside other elite athletes at the University Satellite, including Kanata Akehoshi (granddaughter of former Cosmic Beauty Akari Kanzaki), Shelley Wong, Yana Christopher, Eva Gallenstien, and Paglia Resphigi. Her journey intersects with broader mysteries surrounding the Daiundoukai tournament and political manipulations by the Solar System Control Committee.