Otto Klopp is a master of mechanics and piloting who served as the chief mechanik for Archduke Franz Ferdinand, earning a reputation as the finest mechanical engineer in Austria-Hungary. A veteran of the Balkan Wars, he becomes the tutor and guardian of Alek, the son of the archduke, after the assassination that triggers the war. Klopp is patient and encouraging, always urging Alek to persevere through failure and learn from his mistakes, but he is also firm and unyielding when Alek’s safety is at stake. His primary motivation is the protection of Alek, for whom he has abandoned his former life and position without hesitation. In the story, Klopp serves as a loyal guide and protector, using his deep knowledge of Clanker technology to keep the group’s walker operational and to navigate the dangers they face. His key relationships include a close, teacher–student bond with Alek and a partnership with Count Volger; though Klopp lacks Volger’s noble status, the two work together as equals in their shared mission. Throughout the series, Klopp remains steadfast in his duty, occasionally countering Alek’s impulsive choices with quiet authority. His notable abilities include expert piloting and repair of mechanical walkers, as well as a strategic understanding of machinery that makes him indispensable during escapes and battles.