The KT-21 is a vehicle from the Rebel Army. It 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 as 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.
- On the side cannon of the KT-21 is a metal plate fixed to it with the kanji "火" written on it. It means "fire" in japanese, so it's most likely the cannon was originally used as a flamethrower.
- Beforehand, this tank was called the Sand Simon and incorrectly affiliated to the Regular Army.
- The KT-21, due to its appearance being similar to the Metal Slug and a Di-Cokka mixed together, is erroneously considered by some fans to be a prototype version of the SV-001.
- Even though it is meant to be an enemy tank, it's concept art features a logo on it's upper half somewhat resembling the P.F. Squad's.
- The concept art for the tank (featured in the gallery below), featured the tank in different designs, one of which would end up being the early version of the Melty Honey (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).