Destroyah is born as a small, crab-like creature in an aquarium, killing many of the fish inside. It escapes and grows much larger, destroying a bridge and hiding inside of a factory. It splits in to many crabs which fight against numerous JSDF forces. Bullets have no effect on these creatures, so the JSDF brings out the flamethrowers, which badly wounds the crabs. It is then known that they dislike extreme temperatures. The JSDF bring out freezing guns, and cooling shells which they use to bombard them. This seems to work, until the crabs merge into a bat-like flying form, which soars off.
The JSDF is desperate, and decides to lure Godzilla and his son towards the monster. Despite protests from others, they proceed with luring Godzilla Jr. knowing fully that Godzilla will soon follow. This new form of Destroyah soon finds and batters Godzilla Jr. Jr. puts up a good fight, but is no match for this larger, more powerful monster. However, Jr. fires one last Radioactive beam, which sends Destroyah crashing into a factory. Just as Godzilla arrives on the scene, Destroyah rises up from the flames of the factory in his final form.
Now that the monster is at full power, he leaps towards Godzilla and his son, knocking Godzilla away, and killing his son with a Micro-Oxygen Beam. Godzilla, now enraged, rises from the ground as Destroyah roars at him, challenging him to one-on-one combat. Destroyah is a viscous foe, even Godzilla in his most powerful form is still having trouble with this monster. It beats Godzilla around, using it's Micro-Oxygen Beams, and sheer mass; but the grief for his fallen son is too much, and Godzilla launches an incredibly powerful atomic blast at Destroyah, causing it to Explode. It soon counters however, because the explosion caused it to turn back into its large crab forms, which overwhelm the king. However, the sheer power of Godzilla's emotion is too great, and he releases a blast, destroying the crabs.
As Godzilla goes into meltdown for his fallen son, Destroyah rises once more, leaping upon, strangling, and then tossing Godzilla away from his son. As Godzilla's spines begin to melt, his Atomic Breath's power increases exponentially, and Destroyah begins to burn, and shred from the blast's heat. Knowing it's about to lose, it flees, only to be frozen in midair by the JDSF. It plummets to the ground, shattering into millions of pieces, finally destroying it.