Creature Girls: A Hands-On Field Journal in Another World Vol. 12 (manga)

Not long after Daisuke and Oritsue were transported to an entirely different world, their fellow university student Fuechi wound up there too. Fuechi happens to be an expert in the Oritsue family style of martial arts, and he’s found a comfortable place for himself teaching the fine points of combat to Repuburiku’s elite forces. Their soldiers have been tasked with taming the wild places of the Death Mountains–bringing them into inevitable conflict with Oritsue himself, who rules over the Mountains as the master of the Midori goblin tribe. Human forces grapple for supremacy against the newly-formed Demon Lord’s Army!