The anime was a joint production between CloverWorks (Rascal Does Not Dream of Bunny Girl Senpai (2018), Darling in the Franxx (2018)) & Wit Studio (Attack on Titan (2013) (seasons 1-3), Vinland Saga (2019).)
The character design for Anya bares a striking resemblance to the main character of manga writer Tatsuya Endo's previous work, a One-Shot called, "Rengoku no Ashe." Both characters have pink hair and wear similar hair accessories, although Ashe is older and has a more hardened personality.
Based on a spy action comedy manga by Endou Tatsuya Serialized in Shounen Jump+.
Actress Bryn Appril has appeared as a Temporary Replacement as both Nightfall & Anya in Different points of the Series. Appril also took over for Anya's Megan Shipman's role on Girlfriend, Girlfriend during the same Time due to Shipman being on Maternity Leave.