Attack of Moguera

(heads up... I suck at drawing robots.)
1957 - Earth gets first contact when a human-like alien race named the Mysterians invades an isolated area in northern Japan. Their home world having been destroyed by a force they only refer to as 'Ghidorah', they demand a piece of Terra to live on and try to force the humans out. The aliens and their giant robot Moguera battle the Japanese and US military, but are eventually defeated thanks to an earthquake disabling their underground base and crippling Moguera. The remaining aliens surrender and integrate into society. Much of their technology is reverse engineered and causes an invention boom.