The writing staff was assembled by the series' head writer, Chiaki J. Konaka, who is known for his work on Serial Experiments Lain and Hellsing.

The story takes place forty years after a mysterious occurrence causes the residents of Paradigm City to lose their memories.

The setpieces are reminiscent of tokusatsu productions of the 1950s and 1960s, particularly Toho's kaiju movies, and the score is an eclectic mix of styles and musical homages.

Positive international reception resulted in a second season consisting of the remaining 13 episodes, co-produced by Cartoon Network, Sunrise, and Bandai Visual.

The city is characterized by severe class inequity; the higher-income population resides inside the more pleasant domes, with the remainder left in tenements outside.

[5] After failing to negotiate with terrorists at the cost of his client's life, Roger Smith is obligated to care for Dorothy Wayneright, a young female android.

Other recurring antagonists are Jason Beck, criminal and con-artist attempting to humiliate Roger Smith; Schwarzwald, an ex-reporter obsessed with finding the truth of Paradigm City and also pilot of the megadeus "Big Duo"; Vera Ronstadt, leader of a group of foreigners known as the Union searching for memories and revenge against Paradigm City; and Alan Gabriel, a cyborg assassin working for Alex Rosewater and the Union.

In an isolated control room, the real Angel observes Roger and her past encounters with him on a series of television monitors.

The final scene shows Roger Smith driving down a restored Paradigm city with Dorothy and Angel observing him from the side of the road.

Keiichi Sato came up with the concept of The Big O: a giant city-smashing robot, piloted by a man in black, in a Gotham-like environment.

He later met up with Kazuyoshi Katayama, who had just finished directing Those Who Hunt Elves, and started work on the layouts and character designs.

[6] From there on, the dealings would be with Bandai Visual, but Sunrise still needed some safeguards and requested more robots be designed to increase prospective toy sales.

[9] The series garnered positive fan response internationally that resulted in a second season co-produced by Cartoon Network and Sunrise.

[14] Following the closure of Bandai Entertainment by parent company in 2012, Sunrise announced at Otakon 2013 that Sentai Filmworks rescued both seasons of The Big O.

The series is done in the style of film noir and pulp fiction and combines the feel of a detective show with the giant robot genre.

Noir cinematographers favoured this angle because it made characters almost rise from the ground, giving them dramatic girth and symbolic overtones.

The recurring Beck is the imaginative thug compelled by delusions of grandeur while Angel fills the role of the femme fatale.

[28] Roger's recurring theme, a lone saxophone accompaniment to the protagonist's narration, best exemplifies the noir stylings of the series.

"[19][34] The Big O's cast of supporting characters includes Norman, Roger's faithful mechanically inclined butler who fills the role of Alfred Pennyworth; R. Dorothy Wayneright, who plays the role of the sidekick; and Dan Dastun, a good honest cop who, like Jim Gordon, is both a friend to the hero and greatly respected by his comrades.

The feature, a "retro chic" homage to Yokoyama's career,[35] took seven years to produce and suffered low sales and high running costs.

Instead, the robots are armed with "old school" weaponry such as missiles, piston powered punches, machine guns and laser cannons.

The book contains full-color artwork, character bios and concept art, mecha sketches, video/LD/DVD jacket illustrations, history on the making of The Big O, staff interviews, "Roger's Monologues" comic strip and the original script for the final episode of the series.

Though it was an easy snap-together kit, it required painting, as all of the parts (except the clear orange crown and canopy) were molded in dark gray.

The kit included springs that enabled the slide-action Side Piles on the forearms to simulate Big O's Sudden Impact maneuver.

[18] Several words appear constantly in the English-language reviews; adjectives like "hip",[27] "sleek,"[44] "stylish", [45] "classy",[32] and, above all, "cool"[43][45][46] serve to describe the artwork, the concept, and the series itself.

[51] Andy Patrizio of IGN points out changes in Roger Smith's character, who "lost some of his cool and his very funny side in the second season."

[60][61] Chris Beveridge of Anime on DVD wonders if this was head writer "Konaka's attempt to throw his hat into the ring for creating one of the most confusing and oblique endings of any series."

Sato, Katayama, Konaka, and Bandai in general received many inquiries from fans in Japan asking for further clarification on the plot and ending.

[5] Katayama describes Paradigm City as the created narrative of Angel, who (alongside Roger Smith only) stands above the story but writes herself a role to play.

[5] According to Katayama, her planned narrative collapses when she becomes jealous of Roger's affinity for R. Dorothy, culminating in Gordon Rosewater's realization that Angel is indeed the creator of Paradigm City.