The mysterious monster Neomegas appears suddenly in town, defeats several other monsters, and leaves. Vice-Captain Kaizaki tries to find out what's really going out, when she remembers the words of her mentor. The terrifying true meaning behind those words reveals itself before Kanata, the GUTS-Select team, and Ultraman Decker!!

Sphere-Neomegas is born from the remaining Neomegas cells. Ultraman Decker and GUTS-Select are forced to fight against its overwhelming power. Kanata and his team are devastated by their inability to accomplish anything, but they encourage each other and begin a counterattack operation, mobilizing all their strength with Terraphaser at the center!