『Isn't that water poisonous…?』


  『Eh, won't your life force get sucked off if you drink that?』


  『Yeah. People who notice that fact won't drink this water… And that's precisely why, there's a chance the enemy has set up a network with devices that can detect those who 『don't drink the water』.』


  Once you drink this, your life force seep out a little along with your mana, so those who have drunk this are displayed differently on 『Passive Detection』 and stuff.

  If the demon's surveillance network is present in towns and similar places, anyone who hasn't drunk this will probably really stand out.

  Although it's possible to decrease the amount of mana you're leaking out using magic, making it looks like natural mana leakage is the best it could manage.

  Even with stealth magic, an opponent at the level of Zaridias would easily see through it.

  Yet by simply drinking this water, no one would pay us any heed even if we walk around out in the open unless they're familiar with us.

  Unfamiliar faces might raise doubt in a rural town, but it should be an everyday occurrence in highways and big cities.

  『So we're pretending that we've been completely tricked… But is it really all right to drink this water? Even if it's necessary for the camouflage, it doesn't change the fact that it's still poisonous, does it?』


  『It's only going to suck up very little amount of your life force, and there's no other poison in it, so it's fine. And even if it causes a problem down the line, detoxifying it is simple anyway.』


  After drinking the water, I do feel that my mana is very slightly getting drained out of my body… but the natural recovery rate of life force is faster than this very small reduction, thus, my life force isn't actually decreasing.

  Babies and elderly might get their life force reduced a bit, but it still won't be fatal unless they're suffering from an illness already.

  And this life force leak phenomenon should be unnoticeable unless it's someone who's capable of controlling life force to a degree.

  This must have been expressly adjusted to achieve that.

  『Uun, I can't really get behind drinking this knowing it's poisonous, but eh, whatever will be.』


  『It's still far better than getting attacked by demons after all, and the people of this country already drink this water regularly, so it should be fine.』


  『Will this work on dragons too?』


  The three drank the water while talking.

  I wasn't sure if this poison would work on dragons… but since Iris's life force is now gradually leaking out, it must be working.

  Though with Iris colossal life force, even water with 100,000 times the poison concentration would barely have any effect on her.

  『Still, humans' waterworks are really amazing. Delivering water into every nook and corner of such a vast country like this…』


  Iris said that on our way to the Sixth Source.

  These waterworks have been around for a long time though… but Iris doesn't seem to know about its existence.

  Well, Iris only began to pro-actively get in touch with humans after I reincarnated after all, guess it's only natural.

  『I never heard talk about Saihill Empire being such a technologically capable nation though, or was there some amazing person living here? …or rather, when did they even make these?』


  『There's various rumors on the Empire's Great Waterworks construction date… but I personally think it was probably created by either an ancient civilization or Mathi-kun.』


  …For some reason, Ruli began to push out theory about me being its creator.

  Time-wise, it's not possible though.

  『No err, I don't think I was born yet when these waterworks were made.』


  『That's true, but I mean there's no one else who could have done it… I mean, you've got to make a vast amount of water flowing from bottom to top if it's really reaching the entire empire right? The only one capable of making such high performance magic pumps would be either Mathi-kun or an ancient civilization, isn't it?』


  I see, she was thinking from magic tool point of view.

  …In fact, both theories of Ruli are correct.

  As this water network is a relic of ancient civilization whose construction involved me.

  Since it would be disastrous if the water network got broken and had the content contaminated by poison, I used my magic to reinforce the network's walls and stuff.

  That might be one of the reasons why this network still remains today.

  …I never would have thought that demons would make use of this water network to collect life force several thousands years later.

  Had I known, I would have installed various traps in the Sixth Source.

  There should have been many kinds of defensive mechanisms in the Source to protect against intruders, but the ones set on the entrance must have been blown to bit by the Mana Reactor explosions.

  『Saihill Empire's great waterworks are a relic of an ancient civilization indeed… Well, seeing the source first thing first should make it all clear.』


  『You say that like it's so easy… Surely the Source must heavily guarded no?』


  『Of course it would. Well, let's just stealthily see how it is there and then go from there.』


  Fortunately, we're currently not that far away from the Sixth Source.

  It should be around noon by the time we get there.

  ◇


  Several hours later.

  We arrived at The Sixth Source without a hitch.

  The place where it's located at looks like an ordinary town.

  There are bars filled with adventurers and merchants carrying fruits on their wagons.

  However… Those all are just a farce.

  Boxes carried by merchants are double-bottomed, under the first bottom are magic devices to detect intruders.

  Adventurers hanging around in the bar may look like the real thing at a glance, but most have the same equipment on them.

  Sometimes there are adventurer parties who do have matching sets, but that's limited to armor.

  When even their weapons are uniform, high chance they belong to the army or something along that line.

  …Lots of buildings in the town are built to protect the Source as well.

  The town is dotted with army garrisons that look like ordinary inns outwardly.

  The town looks like a simple ordinary town from outside, but the moment you set foot in it, it should be obvious that it's no ordinary town.

  There's probably no civilian at all living in this town.

  The Map shows this as an ordinary town, but it's probably a camouflage to hide the fact that this town is an important defense point.

  They probably shoo away any civilian who cluelessly wandered off to this town by chance after fashioning some kind of reason.

  『Unn, getting closer than this seems difficult…』


  『It doesn't feel like a normal town does it… But I don't sense demon-ish mana. We'd probably manage getting closer without being seen if we used stealth magic.』


  About one kilometer away from the Sixth Source, Ruli probed for the surrounding mana and murmured.

  Indeed, there is no detectable demon-ish mana around.

  『…We'll go to the source later, let's look around the surface for a bit.』


  『Later… Slipping through all these guards? Is such a thing possible?』


  『Forcing our way through them would be simple enough, but slipping in without getting found out would prove difficult… Unless we take the backdoor that is.』


  Alma's expression turned quizzical after I said that.

  『…The Source is an ancient ruin right? How'd Mathi-kun know about its backdoor?』


  『Detection magic for that purpose exist.』


  Of course, in reality, I simply have the blueprint memorized.

  It might have undergone some structural changes while I was reincarnating, but since the Source was made so that it couldn't be remodeled too much, it cannot have changed that greatly.

  It's possible to investigate underground locations if you get a bit creative with detection magic, but the current me can only get to shallow places with 『Passive Detection』.

  I could get below that if I used 『Active Detection』 by scattering my mana around and probing the surroundings, but that'd send me straight me to the surveillance network.

  …Our enemy probably won't notice if they consist of only humans, but in this situation where demons are likely to be involved, the security can't possibly that lax.