The insert included with the 11th volume of Hajime Isayama's Attack on Titan manga is announcing this week that the story is spawning another series in Kodansha's Monthly Shōnen Sirius magazine. "Another story" in the Attack on Titan world will begin in the October issue of Monthly Shōnen Sirius on August 26.
The wraparound jacket band on the 11th manga volume notes that the original series has over 23 million copies in print. The volume's insert also announced that Spike Chunsoft is developing a Nintendo 3DS game for release this year.