From MangaHelpers:

Kurono, a middle school girl, has summoned a demon to grant her the power to wreck the world. However, the demon says it always seems like it's people who have no friends who ask for that sort of power, and he doesn't really want to do it anymore. Kurono insists that she's only alone because she doesn't need friends, and she ends up making a deal with a condition. If she can make friends that she can keep till graduation, then she'll be granted the power to wreck the world. For Kurono, this may end up being a very difficult task... [tethysdust]