First Lieutenant Wilibald Koenig serves as commander of the 3rd Company in the V601 battalion under Tanya von Degurechaff's command within *The Saga of Tanya the Evil* franchise, appearing in the crossover *Isekai Quartet 2*. He utilizes standard Empire military equipment: an Elinium Type 97 Operation Orb, rifle, and flying gear. Koenig possesses a tall stature and sharp facial features defined by a pronounced chin and small eyes. His long dark brown hair is consistently tied in a low ponytail. His reserved and disciplined personality manifests as unquestioning obedience to orders and steadfast loyalty to comrades, masking an underlying passion. Within *Isekai Quartet 2's* school setting, Koenig participates in group activities. He plays baseball on a team including Naofumi Iwatani ("Shield"), reacting calmly to Naofumi's presence. Later, he joins Kazuma Satou, Vooren Grantz, Rhiner Neumann, and Aqua in retrieving alcohol ("red stuff") from the principal's office. Koenig assists in disabling a laser trap during the operation but is subsequently eaten by a summoned giant toad security measure, resulting in detention for the group. He corrects Aqua when she refers to him as "horse face." His extensive military background includes participation in the annihilation of Dacia, the Osfjord landing, Western Front operations against the Francois Republic, engagements in North Africa, and combat against the Russy Federation on the Eastern Front. He retained his position when the 203rd Battalion was reorganized into the Salamander Kampfgruppe.