Director Masaki Tachibana based the "feel" of London from his own honeymoon to the city, in addition to photos provided by their research team.
The fantasy substance known as cavorite actually originated in H.G. Wells novel, "First Men On The Moon." The substance is a staple in steampunk fiction.
The opening theme song lyrics are in English, this was done to compliment the English setting. The filmmakers also cited 007 as inspiration.
Although a show about spies was what was first pitched, Ichirô Ôkouchi recalls one early idea floated was a story where high school students take over Japan. Ultimately it was Masaki Tachibana who decided to set it in 19th Century London.