The shows main plot is a very hard one to understand at first. 40 years ago, a strange event occurered, causeing the residents of Paradigm City to lose their memories, Thereby called "The Incident". Enter Roger Smith, a negotiator, who helps to solve the mystery of Paradigm City, And his weapon, a megadeus (called "Big O" by Roger, hence the title of the anime) with some awesome powers. But even after "the Incident", there seems to be some strange occurances coming up in the "city of lost memories".
- Realm of Mecha
- Paradigm City
- Christmas Tree 1, Giant Mecha 0
- Cast In The Name Of God -Ye Not Guilty