The Seamstress is a machine created by the Fabrication Machine in order to track down and capture the Stitch Punks. It is a snake-like monster with three spools attatched to the inside of the monster's fabric-like body. The Seamstress also has a pair of three needle-like legs and an extra pair of scissor-like claws and dons a doll face. In order to capture its victims, the Seamstress utilizes hypnosis, in which the monster uses the corpse of a desceased Stitch Punk and produce blinding flashes of light emitted from the corpse to induce the hapless victim. The Seamstress binds its victims with yarn produced from the spools in its body.
The Seamstress captured 7 and 8, causing 9 and the others to follow it to the factory. 9 goes inside the factory and witness 8 having his soul get extracted from the Fabrication Machine. 9 used a dummy to fool the Seamstress and lures the monster to him. The dummy, attached to a rope, pulls the Seamstress and hoists it to the rotating gears. 9 manages to release 7 from the Seamstress's belly and the snake monster get crushed and destroyed.