In the 1960s, two astronauts, Fuji and Glenn, are sent to investigate the surface of the mysterious "Planet X". There they encounter advanced and seemingly benevolent human-like beings called the Xiliens and their leader, The Controller. The aliens usher the astronauts into their underground base, and moments later, the surface is attacked by a creature the Xiliens call "Monster Zero" the astronauts recognize as King Ghidorah, a planet-destroying monster that had attacked
