Prologue In the midst of an expansive white room with basically nothing in it, I, Keima Masuda, was checking my dungeon map. “...Hey. Why’s there only one room and one hallway in this dungeon? I’m not even gonna count the entrance.” “My dungeon’s all about beating down intruders with monsters! I heard that’s the best thing to do!” I don’t know who told her that, but the girl who just brushed aside her waist-length golden blonde hair and grinned with her hands on her hips was my partner, Rokuko. I had just become the Dungeon Master of this dungeon a few minutes ago, making both it and this girl my responsibility. The girl, by the way, was the physical avatar of the Dungeon Core. Which does in fact mean that she, not I, made this terrible dungeon that ended as soon as you entered it. And of course... the heart of this dungeon—the Dungeon Core—was placed in the sole existing room. But the map I was looking at also showed eight red dots in that room. The word “Bandit” was displayed above each one as supplementary information. “O-Oh, I get it! These, uh... these bandits are monsters protecting your dungeon, right?” “Ah, no! Those are the intruders!” Rokuko said something unbelievable with a broad smile on her face. Yeah... yep. They do look like enemies on the map. I don’t know what I was expecting. As far as I could tell from the map, the bandits seemed to be surrounding the Dungeon Core. ...And I was in the Master Room, located right within the Dungeon Core. The Master Room was an odd, pure white expanse without any walls or even a floor. It was about as wide as a gymnasium, leading me to believe that it might have also served as a storeroom. If I were to take even a single step out of this bizarro world, I would be surrounded by all of the bandits. The Dungeon Core itself was about the size of a basketball, so how could a gym-sized room fit inside of it? ...It would probably be a waste of time toeven think about it. “So, Keima. Would you mind killing all of these bandits for me?” Without blinking an eye, my partner asked me to do something pretty crazy. Honestly, I kind of just want to cradle my head and groan... But it’s still too early to give up. Dungeon Masters can expend Dungeon Points (DP) to make rooms, set traps, and summon monsters. Although the only thing you could do once the core room was invaded by intruders was summon monsters, you still had a fighting chance at survival as long as you had DP on your side. Or at least, that’s what I thought before I realized the grim truth. “...Uh, it looks like we’ve only got 9 DP left. What can we do with that?” “Hm? That’s not even enough to summon a goblin. Those cost 20 DP.” “Still, you need to do something about this.” My last hope, vanquished. “It cost me a whole 1000 DP to summon you, Keima. Don’t expect me to have any left over after that.” “Oh wow, [I] cost you that much DP? Huh. Nice...” Without DP, you can’t set traps and you can’t summon monsters. In short, this dungeon had no meandering hallways, no traps, no monsters, no stash of DP... and its singular room had been conquered by bandits. This dungeon’s already completely friggin’ screwed.