The Japanese government has devised a new weapon, dubbed the Dimension Tide, in their fight against radioactive monster Godzilla (Toshiyuki Nagashima). During a test, the Dimension Tide creates a wormhole through which a giant flying creature arrives and deposits an egg before fleeing again. This egg hatches many flying Meganulas that crave energy to give to their queen, the enormous Megaguirus (Tsutomu Kitagawa). Once awake, the Megaguirus faces off against Godzilla with humans in the middle.