"[2] The series takes place in a fictional universe, where a worldwide epidemic of a virus, the Galatea Syndrome (ガラテイア症候群, Garateia Shoukougun), has turned part of the population into guignols (ギニョール, Giniyōru), zombies which resemble marionettes.

Opposed to the queen's rule is Le Sénat: consuls Richter (リチテライツ, Richiteraitu) and Valentine (バレンチナイツ, Barentinaitu), chancellor Meerschaum (ミアシャム, Miatsuyamu), and regent Jasper (ジャスパー, Jayasupā), all of whom have been governing for a century.

They are soon joined by pianist Celestite "Celes" (セレスタイト, Seresutaito), who has lived under the identity of her twin brother, Elestial "Eles" (エレスチャル, Eresutiaru) after a guignol attack left her the only surviving child in her town.

They periodically encounter Berthier (ベルチェ, Beruchie), the unofficial orchestra's former pianist whose violence drove his beloved, Lucille, away and who was resurrected by Le Sénat after his suicide.

Other reoccurring characters include Spinel (スピネル, Supineru), a spy for the queen who can manipulate her voice and whom Lucille befriended when she snuck into the all-male monastery as a child.

[39] Writing for School Library Journal's blog Good Comics for Kids, Snow Wildsmith reviewed the first volume positively, and wrote, "The elements her fans adore are all there: beautiful characters, gender ambiguity, horror themes, blood and gore, and, of course, gorgeous costumes.

[40] David Welsh of Comic World News had more mixed feelings about the first volume; although he praised the aesthetic, premise, translation, and guignols, he wrote that Yuki's work would be more appealing "if she could just strike that balance between creative focus and intellectual abandon and emotional shamelessness.

[42] While finding aspects of the setting and costume design historically confusing and trying on the reader's suspension of disbelief, Rebecca Silverman of Anime News Network wrote that the Gwin's backstory, the quick pacing, Yuki's detailed art, and her frightening portrayal of zombies made the third volume "a winning entry in an already fascinating series.

"[43] Silverman had mixed feelings about the dense page layouts: according to her, they contributed to the narrative suspense, although they affected the reader's ability to easily read the volume in places.

[43] In her review of the fourth volume, Silverman praised the character development and Yuki's ability to create mysteries, although she wrote that not all readers would enjoy the numerous plot twists.

[44] Another reviewer for Anime News Network, Carlo Santos gave the third volume a C-; while he praised Yuki's illustrations and ability to create "dramatic revelations," he wrote that it was overshadowed by the confusing and cluttered narrative.

She, however, expressed her feelings of annoyance and frustration with the conclusion of the fourth volume, which saw the female characters left behind on purpose by the male members of the orchestra and then Eles' kidnapping by Berthier.

Reviewing "Camelot Garden", she enjoyed it less than Grand Guignol Orchestra, and wrote that the short story contained an implicit reference to Lewis Carroll's children's novel Through the Looking Glass (1871) and its character, the ever-sleeping Red King.