Sylia von Bernstein (シリア・フォン・ベルンシュタイン), a high-ranking imperial knight in the Imperial Guard, initially served as the hero of the Wales Tributary Alliance. Hailing from the influential Bernstein noble family of Wales, she became a general to protect her homeland from threats like the Duke of Blankenheim's territorial ambitions. Her primary mission is hunting the space pirate Sara Scorpion, whom she considers a worthy opponent due to her determination and courage, though Sylia disapproves of Sara's dishonorable methods.

During her pursuit, Sylia fell into a trap where Sara directed a warship's blast toward a civilian city. Sylia blocked the energy blast with her shield to protect the citizens until her strength failed, resulting in her capture by Sara. Following her capture, aristocratic antagonists subjected Sylia to extensive physical and sexual torture, including confinement, electro-massage devices, and coercion into humiliating confessions. She endured while maintaining her moral convictions, criticizing her captors' cruelty despite her vulnerable position. Her ordeal included being forced into sexual acts with Sara and others under duress.

Sylia underwent a significant physical transformation when aristocratic experiments turned her and Sara into futanari (hermaphrodites). This permanent alteration caused near-insatiable lust, affecting her long-term existence. After the Duke granted her limited freedom within the castle, she formed an alliance with Sara, leading to their mutual escape and retaliation against their tormentors. In the aftermath, Sylia shifted allegiance to join Sara's crew, becoming her right-hand woman and lover. They achieved a position of power, implied to be queens or empresses, and enacted retribution by enslaving their former tormentors. Her character arc concludes with this partnership focused on creating a better galaxy, though she remains permanently transformed.