[4] The title character is loosely based on the historical figure Chevalier d'Éon, who lived in the middle of 18th-century, pre-Revolutionary France under the reign of Louis XV.

[6] The story begins in Paris 1742, when the body of a woman named Lia de Beaumont is found in a casket floating along the Seine.

D'Eon de Beaumont, Lia's younger brother and a knight in service of King Louis XV, takes it upon himself to investigate his sister's mysterious death, along with the strange disappearances of a number of French women.

By order of the King of France, he is to recover the Royal Psalms which is linked to the mysterious death of his sister and the case of the missing women.

This is what made the Chevalier d'Eon a "fitting figure to cast as protagonist" because he embodied all of the contradictions of that time period, which Ubukata lists as "Wealth and poverty, faith and heresy, diplomacy and conspiracy, king and commoner, even the devastation of war and the flowering of culture."

"[8] toi8 of Studio 4°C was initially asked to work on the series' character designs, but the job was passed on to his wife, Tomomi Ozaki, due to time constraints.

We stayed true to the plot given to us initially and I feel we actually added depth to it.Scriptwriter Shotaro Suga was contacted by Tetsuya Nakatake at the beginning of the project, and agreed to work with them when he was informed that Tow Ubukata and Kazuhiro Furuhashi were taking part in the production.

He described the script readings for Le Chevalier D'Eon as "ever more intense" than his previous projects, and that they all "kept on debating to scrutinize each and every detail."

Muto was present during the productions' post-recording sessions, primarily because he believed that it would be easier for the staff to have a writer on-hand in case problems arose during recordings.

[12] Art director Hiroshi Ono stated that he initially could not make up his mind whether to work on this project or not, saying "The information they gave me was enough to see that this was not going to be a straightforward job.

He utilized different reference materials for his designs, saying that he "relied on images in books and on the web" as well as films such as Fanfan la Tulipe and The Affair of the Necklace.

[15] toi8 was initially asked to work on the series' character designs, but the job was passed on to Tomomi Ozaki due to time constraints.

Aya stated that she drew inspiration from the first illustration she was shown, which was of "D'Eon, splattered with the blood of his victim, [walking] in the burning city of Paris holding Lia's hands.

Tasha Robinson of Sci Fi Weekly praised the details in the designs, but stated that "the characters all have a flat-faced samey look; their costumes get far more attention than their faces, and the results are pretty but bland.

"[32] Theron Martin of Anime News Network said "Background art varies a little more, from slightly rough to stunningly gorgeous, with some CG-crafted shots of Versailles rivaling even the exquisite detail of Gonzo's best work.

Though the series does use some still scenes, neither they nor any other short cuts can be found in the well-choreographed sword fights, where the attention to detail (especially in rare anime shots of critical footwork) and shifting perspectives more than makes up for slight failings elsewhere.

[34] Similarly, Brett D. Rogers of Frames Per Second magazine praised the design and animation, saying that they are "beautifully rendered in rococo and gothic style to create the look and feel of 18th-century France", though also stating that the "CGI is used to good result in reproducing the vast, opulent spaces of Versailles, but the transitions between these effects and the main body of animation are a bit coarse.