Log Horizon Novel Volume 5 is written by Mamare Touno.

In the sort of autumn afternoon that leaves maidens sighing, new enemies arrives in Akiba! And these enemies are more terrifying than any monster--they're human. Worse, their target is the very system at the heart of the city--the Round Table Council! Will the tenuous government that Shiroe's worked so hard to build survive this latest threat? Find out in volume 5 of Log Horizon!