An army of loyal samurai plot to revenge their unjustly executed lord

A pollution monster named Hedorah comes from outer space. First it terrorizes sea, then it goes on land where it encounters the big G. After it's after the fight with Godzilla it retreats, only to reappear again in a flying form, it's starts to kill people. Then it takes on it's final form, that's when the Big G comes and the battle that decides the fate of the world begins. Written by Spaceroach