After the U40 warship, now dubbed the Ultria, successfully destroyed a significant portion of the Heller fleet the invaders retreated to their base on Saturn's moon of Titan to devise a new plan. The Heller aliens sent a small cat monster named Hell Cat to infiltrate the space station EGG-3. Upon doing so Hell Cat managed to kill off an entire section of crewmen and managed to evade the Scientific Defense Guard with his ability to turn into a normal kitten. After attacking Pigu, Hell Cat aimed for Mutsumi only for Ultraman Joneus to attack the giant feline. Joneus managed to lead Hell Cat into a section he managed to seal off so nobody else would get caught in their fight. To assist Joneus, Pigu and an Ultria drone managed to activate a bomb, blowing both the hero and Hell Cat into space. Once Hell Cat reached maximum size he was finished off with Joneus's Planium Beam and one of the Ultria's cannons.