The King of Decay and the black stone

 
 ”Having the strength to even corrode mythril, the King of Decay is the worst king. As one of the beings in existence called the Demon King, if he ever resurrects, we’re finished.” (Jay)
 
 Jay explained about the King of Decay. But why was such an atrocious being sealed away on this island.
 
 ”First time I’ve heard of him. But who in the world made such a seal?” (Wirk)
 ”An ancient magician, apparently. It was my father who found the seal, but there was an ancient document left behind near the seal. It also mentioned the magic black stone.” (Jay)
 
 I see. And Jay’s father was the previous generation’s king of the dwarves.
 
 ”The only thing that the King of Decay cannot corrode is the magic black stone, which was produced from magma. That’s why the magician back then used it to complete the seal.” (Jay)
 
 I see. Certainly, the magic black stone is resistant to corrosion.
 
 ”However, the ancient document stated that the seal wouldn’t last forever, but would weaken over many months and years and eventually be broken. My father thought that, as it was, the seal would come undone in the near future, and so he devoted himself to the metallurgy of the magic black stone. But in the very end, he passed away and the mission was passed on to me.” (Jay)
 ”I see. But how did that lead to blacksmithing with magma?” (Wirk)
 
 I thought of something that made me think “there’s no way”, but I asked just to make sure.
 
 ”The magic black stone seems to have been completed after the ancient magician continuously used magic while making use of the magma for three days and three nights.” (Jay)
 
 Eh? Three days and three nights for only that much?
 
 ”They repeated the process many times until a stone of that size was completed, and the seal was successfully made.” (Jay)
 
 I was curious as to how much skill this ancient magician had, but as expected, he really was ancient, huh… I get the feeling that it took a lot of work.
 
 ”However, dwarves can’t use magic. In addition, we couldn’t refine the magic black stone in any way with the furnace we’d been using up till then. So my father came up with the idea of using magma directly. A seal is impossible for us. In that case, if we could skillfully grant the ability of the magma to our equipment, we’d be able to make equipment which wouldn’t corrode. If we had that, we could at least fight.” (Jay)
 ”… no way, he seriously said they were going in that direction…” (Wirk)
 ”… what? You got a complaint?” (Jay)
 
 Jay glared at me, displeased, and said so.
 Ye~ah, well, I’m not exactly complaining, but it kind of feels like he went in a completely unexpected direction.
 
 The dwarves’ skill in blacksmithing is firm, something I even think is superior, yet even so, they seem to be inflexible in some ways. The dispute they had with the founder of magic architects was partly due to the fact that they couldn’t accept new techniques.
 
 ”I don’t mean to say it like this, but with the way the dwarves are doing things now, they won’t be able to build equipment that can stand up to that King of Decay even if they spent their whole lives.” (Wirk)
 ”Wh-, what did you say! You don’t even know what you’re talking about!” (Jay)
 
 I do know about this. I’ve made this magic black stone before.
 
 ”Seems I found a way better test material than iron.” (Wirk)
 ”Unii~!”
 
 Uni also cutely pumped his fists. Having heard what I said, it seems Uni became motivated. Seems I’m going to need Uni and the moles’ cooperation in order to do this.
 
 ”Test, you say? What the h**l are you thinking?” (Jay)
 ”I’m now going to do the metallurgy for the magic black stone you guys need.” (Wirk)
 ”Ha?” (Jay)
 
 Jay blinked in surprise. Then he glared at me with sceptical eyes.
 
 ”You know. I said it just now? No matter how many times we dwarves tried, we couldn’t do the magic black stone’s metallurgy.”
 ”That’s because you used an ordinary furnace. So it’s impossible no matter how many times you try, and moreover, it’s meaningless to directly bestow the component of the magic black stone from the magma.” (Wirk)
 
 The black magic stone can be produced by using the ore that has hardened from lava that has cooled under certain conditions. But the ingredients themselves are still weak when in a viscous lava state, so no matter how much magma is used to strike it, it will not seep into the tool.
 
 ”You! So you’re saying that everything that we’ve done has been meaningless!” (Jay)
 ”That’s right.” (Wirk)
 
 The other dwarves are grumbling too, but it’s better to say these things outright.
 
 ”Anyway, we can’t just keep going on and on about this, right? Judging by the state of that crack, it won’t last much longer, so if the King of Decay’s revival is such a bad thing, then have a little faith in me.” (Wirk)
 ”That’s right! I don’t think Wirk is a human that’d say careless things either, and he has amazing techniques. This isn’t the time for Papa and everyone to be so obstinate!” (Eph)
 
 Eph shouted that out at the top of her voice, then Jay crossed his arms and began thinking.
 
 ”… I understand. But if you say that and still can’t do it…” (Jay)
 ”I got it, I got it. I’ll never show my face here again, and if you like, I’ll even leave the island.” (Wirk)
 ”Wha-! Wai-, Wirk, that’s a bit…” (Eph)
 
 When I confidently informed Jay so, Eph had a worried look on her face. I should probably follow up a bit here.
 
 ”Don’t worry. I won’t say something I can’t do. Rest easy.” (Wirk)
 
 I placed my hand on her head as I told her so. Then Eph’s face turned red.
 Oops. I think I unconsciously touched her too casually!
 
 ”Ah, fine. You, if you can’t do it, you’re definitely leaving. And I won’t allow you to take my daughter with you.” (Jay)
 
 Then Jay, with blood vessels all over his face, told me so threateningly.
 To be that serious about it, after all, you do care about your daughter, don’t you?
 
 ”Wirk. I also dislike you leaving-noja.” (Bamboo Princess)
 
 The Bamboo Princess came closer, then intently gazed at me and said something similar to what Eph said.
 
 ”Yes? Oh, that’s why you shouldn’t worry. Believe in me more.” (Wirk)
 ”… is that all?” (Bamboo Princess)
 ”Yes?” (Wirk)
 
 I’m confident I can do it, but is everyone worried about me? I roughly told the Bamboo Princess that I’d be fine, but she seemed dissatisfied about something.
 
 ”You really don’t get it at all-noja!” (Bamboo Princess)
 
 Then she got angry and puffed up her cheeks. Why!
 
 ”Just a minute, Wirk. You know what?” (Eph)
 
 Eph came close to my ear and whispered what the best thing to do for the Bamboo Princess was.
 
 Huh? It’s that?
 
 ”Uhm, so, that’s why I’ll be fine, ok?” (Wirk)
 
 I placed my hand on the Bamboo Princess’s head as I told her this. Then her puffed up cheeks deflated, and she peeped at me with an adorable smiling face, giggling.
 I kind of offended Eph when I did it to her earlier, but I don’t really understand girls’ feelings.
 Anyways, I need to be out of here as soon as possible or I won’t be able to do the magic black stone’s metallurgy…

 [TL: Congrats to our MC, because you have just earned [Achievement: Start a Harem]! Yes, I know, I could have seen this coming, but nothing happened that could properly justify it until now. Anyways, I’ve adjusted the tags and such to include Harem, both on this site and on NU. Raise your hand if you’re tired of harem stories…]