No it's actually the other way around, because this is the side story. If u read this before Another, it will spoil the main story
Umm i think it's as @anon said
no, the other way around.
(may contain spoiler) in the first part of another, we don't know whetever misaki is real or not yet
You have to read this after another. It's that word prequel /sequel thing. Although it is the prequel, it explains the main story too much
Read this before another