Gongilgan is a DemoniCarcass kaiju that emerged when damudoxin, a type of nanomachine that interferes with the cells of living organisms, went out of control. It fused and absorbed various kaiju genes.

It heads towards the Necromass headquarters, where damudoxin is being researched and developed. This iss in order to destroy its only weakness, the anti-damudoxin. During its attempt it absorbs Yuki, the son of the Necromass CEO, in an attempt to gain a "soul," causing it to evolve into its second form.

In its second form, Gongilgan’s antennae, which extend from both eyes, glow and flash resembling tears. It can then unleash a barrage of beams from its entire body. These antennae can also ensnare enemy attacks, rendering them powerless. If an enemy grabs hold of the antennae, it will release an electric shock to counterattack. The protrusions on its knees are detachable and can be wielded as a shield to deflect attacks or used as swords. It can also release beams from its mouth, as well as a full-charged beam from its abdomen.