The KT-21 is an unused vehicle from the Rebel Army.
The KT-21 was supposed to appear in Metal Slug: Super Vehicle-001, but it was scrapped for unknown reasons. This vehicle only appears in the game's data as an unused tank.
While at first glance it seems to be a unique tank, its animations and other unused sprites related to it are similar to the Di-Cokka's. This tank could either be an early version of the Di-Cokka or a variant.
The KT-21 has two attacks. The first is firing a shell from its cannon; the shell's sprite is unique. The second attack is spewing out fire from a side-mounted flamethrower. Just like the Di-Cokka, the KT-21 stays destroyed while a Rebel soldier pops out with an RPG. Once he flees or dies, the KT-21 fully explodes.
- Fixed on the side cannon of the KT-21 is a plate with the Kanji "火" written on it. "火" means "fire" when translated from Japanese.
- The KT-21, due to its appearance being similar to the Metal Slug and a Di-Cokka mixed together, is erroneously considered to be a prototype version of the SV-001 or a Regular Army MBT called the "Sand Simon".
- Even though it is meant to be an enemy tank, it's concept art features a logo on its upper half somewhat resembling the P.F. Squad's.
- The concept arts (featured in the gallery below) features the tank in different designs, one of which would end up being the early version of the Melty Honey (in the upper left corner). The unused tank sprite is based mostly on the tank design on the bottom right area, but with the side-cannon from the one on the bottom left.
- The tank is based on a French Char Somua S35/B1 Bis tank, which is used in WWII for the Free French Forces and the Germans (captured examples).