UMP40 is a Tactical Doll (T-Doll) featured in the mobile strategy game 'Dolls' Frontline.' As one of the many anthropomorphized firearms in the game, she is based on the real-world Heckler & Koch UMP submachine gun. UMP40 is known for her bright personality and mischievous demeanor, often engaging in playful banter with her squad mates. In combat, she serves as a submachine gun unit, providing close-quarters firepower and support. Her character design, voice lines, and interactions with other dolls make her a beloved member of the 'Four Sisters' within the game.