Their mission is to help Ultraman fight space dinosaur Zetton, which was reputed to be the strongest kaiju in the original TV series and one of the most formidable nemeses for the superhero.

Continuing where the previous story left, Mechazam proceeds to attack EX Zetton in a mad fury but almost perishes in the molten lava until Mebius saves him, despite being heavily injured by EX Zetton.