Movie
Description
Matheus Johann Weiss holds the dual position of Vice Commander and 2nd Company Commander within the Imperial Army's elite 203rd Aerial Mage Battalion. Initially assigned to the Eastern Army, his appointment directly resulted from Tanya von Degurechaff's selection. Weiss's military rank ascends from First Lieutenant to Captain and ultimately Major throughout his service.

Physically, Weiss possesses a curved face, black hair, and black eyes. He consistently wears standard military attire in casual settings and switches to specialized battle gear—including the Elinium Type 97 Operation Orb, a rifle, and Empire Flying Gear—during combat operations.

Weiss balances a prudent nature with adaptability, effectively managing and disciplining subordinates while retaining their confidence. He demonstrates consistent concern for their welfare, actively attending to battalion logistics and morale. This reliability earns him significant trust from Tanya, leading to regular dialogue that sometimes escalates into bickering. Weiss maintains steadfast loyalty to Tanya yet harbors apprehension toward her methods, frequently reacting with shock to her statements or actions. He fosters positive relationships with fellow officers like Grantz and Serebryakov, showing particular consideration for Serebryakov as one of the battalion's few women.

In the *Isekai Quartet: Another World* narrative, Weiss actively participates in combat against swarms of small golems alongside Tanya, Grantz, Raphtalia, and others after their class is transported to another world. His group continues fighting while separated, later reuniting with the main ensemble at a village. He contributes to the collective effort against golems guarding a critical facility, participating in the tactical plan to teleport large golems into a hole for destruction by Megumin's Explosion magic.

Following the 203rd Battalion's reorganization into Kampfgruppe Salamander, Weiss receives a promotion while retaining his role as Tanya's vice commander. He assumes full command of the 203rd during Tanya's absences and additionally serves as a coordination point between different battalions within the regiment. This coordination role initially creates tension with an infantry battalion major until the unit is replaced with elite paratroopers, resolving the command structure issues.