The December issue of Hakusensha's Melody magazine has announced that Himitsu Season 0, the spinoff manga by Reiko Shimizu, is set to enter its final story arc. The conclusion will commence in the magazine's February 2027 issue, scheduled for release on December 25. First launched in October 2012, the series functions as a prequel to Shimizu's original Himitsu - Top Secret manga, detailing the history of agent Maki. The publication history of the spinoff includes a two-year hiatus that began in August 2021, with the series returning to serialization in October 2023. Hakusensha most recently released the 12th compiled book volume on July 3. The broader franchise has seen several adaptations, including the 2008 Top Secret The Revelation anime by Madhouse, a 2016 live-action film, and a live-action series that premiered in January 2025.