Hagurumon

A mutant Machine Digimon shaped like a gear. There are countless gears built into its body, and the gears are constantly rotating. For that reason, if even a single gear is missing, all of the gears in its body stop rotating, and it becomes unable to maintain its vital functions. Hagurumon possesses the special ability to send a computer virus to its opponents in order to manipulate them at will, and that ability is exploited by fiendish Digimon. However, because Hagurumon itself doesn't have any sense of self, it doesn't even know it is being misused. Its Special Move is burying a black gear with a built-in computer virus within the body of the opponent, driving them mad (Darkness Gear).