Last February 26, 2015, Dengeki G's Magazine made an announcement[1] with "Love Live! Sunshine!! Start" (ラブライブ! サンシャイン!! スタート Rabu Raibu! Sanshain!! Sutāto) as its topic title.
The only contents found on the said announcement are the words "Coming Soon...", and this image with the words "Tasukete, Rabu Raibu!" (助けて、ラブライブ lit. Help me, Love Live!)":
However, on March 27, 2015, Dengeki G's Magazine made another announcement[2] about the same topic. The same teaser image was included but this time, with 8 other girls in it as well.
This project is announced to start on April 30, 2015. It is currently unknown whether this project will be a new anime series, manga serialization, or something else.
References:
⋆Ragnarok6354⋆ 14:11, March 27, 2015 (UTC)