Plot Summary:During World War II, robotics expert Professor Koga was assigned by the Japanese military to create robotic soldiers, which would be turned loose against the allies. That is, until he got word that his son, Tsurugi Ryuusei, had been killed in battle. He then washed his hands clean of the whole thing, locks away the prototype, and takes the plans with him. Four years later, Makoto Dolbara, A former colleague of Professor Koga, becomes leader of an organization called the Neross Empire. He then orders his robots to kill Professor Koga, who survives the attack. He then heads for the secret base, and activates the prototype, which eas designed to look like his son. however, despite the Professor's pleas, the robot (Metalder) showed little reaction. The robot then tries to respond to the professor's cries, in which it would be too late. Seeing his dead "father", the robot then swears that it would be the Neross' worst nightmare.
在二次大战期间,古贺博士仿照战死沙场的儿子的容貌,制成机器战士作怀念。但超人机米达完成后,战争已经结束,于是,博士没启动它,它便开始了长达四十多年的沉睡。 战后,古贺博士到美国太空总署参与火箭研究,成就非凡。当博士得知悉尼罗斯帝国要向人类发动进攻的时侯,他便赶忙回国,启动超人机米达。