The Diet Tank (also known as a Belly Balloon) is an Unversed found in Kingdom Hearts Birth by Sleep Final Mix. The player can transform into this Unversed using the exclusive Illusion-D command. It shows a resemblance to the Tank Toppler in Kingdom Hearts Birth by Sleep
The Diet Tank has a massive, circular body that ranges from a dark indigo to a orchid color. Its head is black, and its red eyes curve together is a pointy formation. It sports two side spike and one long, cylindrical spike on its head. Out of its body, two pudgy arms are seen out of the side. The arm is short, and is covered with a hook like thing ringed by a steel band. The bottom half of its body is ringed by a steel structure—spikes are seen on the top. On the bottom of each spike is a single plate that will split into two near the bottom of the Diet Tank's body. From the bottom of it, two small feet somewhat support the Diet Tank.