The Diesel Ressha is a maroon diesel locomotive-themed Support Ressha. When in full form, the locomotive is attached to a train comprised of multiple units (turning it into a diesel multiple unit, or DMU) with a boxcar and a flatbed with cargo boxes at the end. Diesel Ressha forms the arms and main body of Diesel-Oh. On its own, the Diesel Ressha has missile silos in it's engine component to fire at targets. The Diesel Ressha is also the oldest Ressha, and is affectionately called "Grandpa" by Right.