Klaus is a commissioned officer in the Helvetian army with the rank of Major, serving as a dispatch rider who acts as a courier between units. He regularly visits the 1121st Tank Platoon stationed at the Clocktower Fortress in the town of Seize. He shares a strong physical resemblance and a similar name with a legendary tank commander known as the Desert Wolf or Miracle Claus, a celebrated war hero from a previous conflict. The platoon member Kureha Suminoya mistakenly identifies him as this hero, a misunderstanding Klaus finds awkward and struggles to correct, as the other members of the platoon often play along when Kureha is present.

Klaus is a serious and professional soldier who takes his duties as a courier earnestly, but he possesses a friendly and approachable demeanor and maintains a warm rapport with the platoon. He is humble and grounded, frequently downplaying his supposed heroic reputation and insisting he is nothing like the legendary Desert Wolf when speaking candidly with the others. His motivations are rooted in a pragmatic sense of duty to his country and a genuine care for the soldiers he interacts with, rather than any desire for personal glory.

In the story, Klaus serves as a vital link between the isolated, peaceful setting of the Clocktower and the wider military situation of the world, delivering orders, supplies, and news. He maintains close friendships with the entire platoon, including Kanata Sorami, Rio Kazumiya, Noël Kannagi, and Filicia Heideman. His most defining relationship is with Kureha, whose idolization of him creates a gentle comedic tension and also serves to highlight his fundamental honesty and humility. He does not undergo a major transformation, instead acting as a stable and reliable presence whose quiet integrity reinforces the series' themes about the value of ordinary people over myths. His notable abilities include his competence as a rider and his military discipline, but his defining trait is his earnest, unassuming nature.