“Giant Robo: The Animation” (1991) IMDb
A clean, safe, cheap, renewable and very efficient source of energy has virtually obsolesced all previous forms of power generation in the near future. However, the revolutionary device has a weakness. Members of the darksome Big Fire Organization consequently obtain the power to black out the planet. A young boy and his personal flying atomic giant killer robot boldly step in their way.
5-year OVA series. “Wagnerian” (says Patrick Drazen) mecha/superhero drama. Based on a manga by the father of the mecha genre (Yokoyama Mitsuteru), but not actually the first of those, i.e. not Gigantor (1958), nor very faithfully adapted I believe. The historical significance of Giant Robo: The Animation lies instead with its status at the head of the largely abominable retro wave where a number of classics were revamped as superficially as possible.
Many characters are based on or ripped straight out of classic Chinese literature and old anime, without introduction or explanation, and the retro designs are mostly annoying. Gigantor shows how mecha worked before they got realistic enough for cockpits. In that vein, Giant Robo is definitely a character more than a machine. Good music incorporating opera, some good animation, some excellent superhero camp (especially the speedy smoker).
This anime encompasses only a story named after The Day the Earth Stood Still (1951): a slightly ironic title when the series actually chronicles the annihilation of several cities that opposed Japan in WW2. The ending promises a sequel.
References here: Neon Genesis Evangelion (1995).