Rewrite:SIDE-TERRA is now available to read for free on ComicWalker! SIDE:TERRA is the manga adaptation of the currently airing Rewrite anime, and features glorious art by ZEN (known for working on the Little Busters! - End of Refrain and Little Busters! Ecstasy manga). Chapters 1 and 9 are up to read while the next chapter will be out on 15th March.
If you’ve missed the previous chapters, you can buy Rewrite:SIDE-TERRA vol.1 from Amazon JP and CDJapan. With vol.2 coming out 27th March, now is a good time to catch up or take a quick refresher in the world of Rewrite!
Source: http://gs.dengeki.com/news/94344/