According to a photo from someone who has already received a copy, the wrap around band on volume 2 of the Zero no Tsukaima Chevalier manga, on sale August 23rd along with volume 1, announces that another TV series of Noboru Yamaguchi's Zero no Tsukaima (aka The Familiar of Zero) light novels has been green-lit. The series will be the fourth and according to the wrap around band, the final series. Further information will be made public through the official website and the October issue of Comic Alive, on sale August 27th.
Announced with the BD Boxes for all three previous series earlier this month, a re-airing of certain "best of" episodes of the past series, called the Zero no Tsukaima Kessaku-sen, will begin this October on Tokyo MX and other channels. The first three series aired in the summers of 2006, 2007 and 2008 respectively.
Image ©Noboru Yamaguchi, Media Factory
Update: Added Zero no Tsukaima Kessaku-sen/Yorinuki Zero no Tsukaima info