Shinwa Densetsu no Eiyuu no Isekaitan - Volume 5, Afterword

An average man is reincarnated in the world of DxD! How do you survive in a world of battle-hungry monsters? With a cheat skill, of course! Devour the competition, becoming stronger with every fight! From the depths of the Familiar Forest, the Beast King will rise. (Harem, Gamer!SI)

In a world fraught with innumerable dangers where living day by day is a struggle, a young man from the modern age transmigrated into such a world, accompanied by a peculiar system made for assassination.

As the ruler of a munitions empire, Tang Mo unexpectedly fell and was transported to an entirely different world, where he also unexpectedly acquired a “King of Munitions” system.In this underdeveloped world, Tang Mo relied on the abilities granted to him by the system to drive the development of the entire world.After all, the desire for civilization conquest had always been the driving force behind progress, and life had continuously evolved between attack and defense over tens of millions of years...So, selling assault rifles to these archers and training knights to be tank operators... there shouldn't be any problem with that, right? XD