The official website for the anime of Natsume Ono's ACCA 13-Territory Inspection Department manga revealed on Wednesday that production on a "new original video anime & musical stage reading" special titled ACCA 13-Ku Kansatsu-Ka Regards (ACCA 13-Territory Inspection Department Regards). The latter part of the video below features Nino (Kenjiro Tsuda) reading a letter to Jean asking him about what they were thinking "that time."
— TVアニメ『ACCA13区監察課』公式 (@ACCA_anime) March 26, 2019
When political conspiracies abound, preserving the peace is no piece of cake. It's up to one deceptively aloof hero to sniff out corruption in this atmospheric thriller.
Ono launched the original ACCA 13 manga series in Monthly Big Gangan magazine in June 2013 and ended it in October 2016. She then launched the ACCA 13-Ku Kansatsu-Ka P.S. spinoff manga in Big Gangan in December 2016, and ended it in October 2017. Ono also drew a single-volume spinoff manga titled Paula to Michel (Paula and Michel) that debuted in December 2017. Yen Press released the manga's sixth volume on February 26.
Ono recently launched a manga titled BADON on January 25. While not explicitly stated to be a spinoff of the main manga, the manga's story takes place in a city named Badon, the same name as the main setting of ACCA 13.
Source: ACCA 13-Territory Inspection Department anime's Twitter account