A Kaiju that attacked the power plants and electricity supply of Isemi city. Neronga is usually invisible but turns visible when it consumes enough electricity. It can fire a beam of electricity by bringing its two feelers and horns together.

Neronga hid itself at the bottom of an old castle well until young Hoshino spotted him inside. However, it turned invisible and appeared above ground, causing a rift in the Earth. Neronga went on to destroy hydropower stations built around the castle one after another, before feeding on the Isemi City electricity stores, making it visible. After firing an electricity beam at SSSP Member Arashi Neronga disappeared.

Neronga later appears at a thermal power plant where neither the SSSP nor the Self Defense Force attacks’ have any effect, and Neronga continues its rampage until Ultraman arrives to fight it. Neronga attacks our hero with body tackles and electric beams, but Ultraman is unfazed and defeats Neronga using his Spacium Beam.