Roanne Demitrich is a 15-year-old Swiss national and member of the Cosmic Culture Club, distinguished by his exceptional intellect and mature demeanor. His calm, observant, and level-headed nature allows him to remain analytical during crises, applying strategic thinking uncommon for his age. As the group's primary strategist, he systematically assesses complex situations to determine optimal solutions based on available resources and constraints.

His composed personality and strategic acumen enable him to form a swift rapport with the central protagonist, Eiji Asuka, leading to his role as Eiji's secondary wingman piloting the SPT-BD-03U Baldy combat unit. Roanne maintains a close friendship with fellow club survivor Arthur Cummings Jr., whose contrasting personality highlights Roanne's stability and reliability within the group.

After a significant timeskip and narrative shift, Roanne participates in a mole operation, during which he slicks back his typically blue hair as part of his undercover activities. Upon completing the mission, he returns to his original hairstyle.

His background as a genius-level strategist and his actions as Eiji Asuka's wingman remain consistent throughout his portrayal. His Swiss nationality and Cosmic Culture Club membership form the foundation of his identity.