Schwanhelt Bulge is the captain of the Sirius Platoon in the Space Defense Force, appointed after the heroic sacrifice of his predecessor, Wataru Yuuki, who died protecting the crew and the galaxy from an invading destroyer. A capable and dedicated leader, he is often perceived as a father figure by his platoon, placing the safety and welfare of his crew above his own personal safety or career.

He once deliberately disobeyed a direct order from a general in the secret intelligence division, choosing to rescue imperiled crew members instead of prioritizing the repair of the platoon's engine, Big One. The confrontation escalated, resulting in him punching the general and rendering him unconscious. As a direct consequence, he was stripped of his captaincy and the Sirius Platoon was dissolved, its members reassigned to other units. His leadership was later unofficially reinstated by the commander of the Galaxy Railways for a critical situation.

His background includes a personal sacrifice; he gave up a romantic relationship to protect those he cared about, and his attempts to contact this woman over the years were unsuccessful. He is approximately 41 years old in one source, and around 39 or older in others.

Anticipating the political fallout from his defiance, he entrusted the crucial Cosmo matrix to the train's mechanics for study and integration into Big One's weapons system. When authorities demanded its surrender, a counterfeit was provided. This foresight ensured Big One was secretly repaired and upgraded while impounded, allowing it to be fully operational for its most critical mission.