The January issue of Square Enix's Monthly Shonen Gangan magazine is announcing on Saturday that Atsushi Ohkubo is launching a new Soul Eater manga series named Soul Eater Not! in the next issue. The new series will run alongside the main Soul Eater series on January 12, 2011.
This manga, as the title indicates, is a spinoff from the original, yet the argument still has to be revealed.
(Source: Anime News Network, Kyō mo Yarareyaku)