ONAs posted on the official site of RG Studios' page and the director's youtube page that feature Backkom shorts that never made it to the main series nor the the DVD release of the main series.
This entry is composed of:
Backkom Feature Trailer - Backkom falling through the roof of CGV; the largest cinema chain in Korea, then taking a seat in the first row of the theater. (2007, 39 sec)
Backkom Filler Animation - Backkom at a library. (2008, 53 sec)
Backkom Song!! - Backkom jumping on a trampoline to a song. (2009, 30 sec)
Backkom's Friends - Backkom causing a chain reaction toppling various characters in the Backkom franchise and in Sheep in the Island. (2009, 40 sec)
Super Backkom - Backkom changing into his Super Backkom form in a portable restroom. (2009, 34 sec)
Tightly - Once again Backkom needss to change into Super Backkom with the portable restroom. This time someone else is using it. (2009, 43 sec)
Super Backkom Technology Test Video - Super Backkom fighting a water monster and rescuing a girl who closely resembles the rescued girl in the Makera Demo. (2012, 63 sec)
Backkom Separate Garbage Animation - Backkom trying to separate his garbage. (2013, 90 sec)