Nine Barthes, whose name is occasionally romanized as Nine Baltic, appears in Gundam Build Fighters as a secondary antagonist. He is the leader of the Flana Institute, an organization that conducts experiments on Gunpla fighters, and serves as the personal manager and physician for Aila Jyrkiäinen. In this dual role, he is responsible for monitoring Aila’s physical condition and providing tactical support during Gunpla battles, often acting as her driver and assistant in tournament settings. Nine Barthes is driven by a single-minded desire to secure victories for his sponsors, and he is willing to employ underhanded methods to achieve that goal. He views Aila primarily as a tool to win matches, showing little regard for her well-being or personal freedom. His cold, calculating demeanor and willingness to manipulate those around him make him a persistent obstacle for the main characters. Throughout the series, Nine Barthes remains largely static, never undergoing significant personal growth or redemption; his role is to represent the exploitative side of the competitive Gunpla world. He is notably not a pilot himself, instead exerting influence through control over Aila and the resources of the Flana Institute. His key relationship is with Aila, whom he treats as a test subject rather than a partner, and he clashes with Reiji and Sei Iori as they work to free her from his influence. Ultimately, his ambitions are thwarted when Aila breaks away from his control, choosing to fight for her own enjoyment rather than as a pawn of the institute.