Rokka: Braves of the Six Flowers (Light Novel) 2

Enemies without...and an enemy within.

After escaping the impostor's trap, the newly assembled Braves of the Six Flowers set off to fight the Evil God--only to find yet another person bearing the Crest! With the clock ticking down on the time until their fearsome enemy awakens, the seven have no choice but to journey through the Howling Vilelands with a false hero among them. To make matters worse, a seemingly invincible fiend commander with connections to several Braves attacks the divided group. They must work together to have even a hope of defeating such an adversary...but how can they, when anyone could be the traitor?