The series inspired Saori Otowa’s DAYS Gaiden spinoff manga, which launched in Kodansha’s Magazine Pocket manga app in October.
The wraparound jacket band on Tsuyoshi Yasuda’s 20th DAYS manga volume revealed last Tuesday that the manga has 4.5 million copies in print.
Yasuda launched the series in Kodansha’s Weekly Shōnen Magazine in April 2013.
Ponycan USA plans to release the series in the United States. Weekly Shōnen Magazine revealed in December that a sequel for the anime series is in the works.