I'm guessing, but it's extremely possible.
　The only way to find out is to get the reject crystal again and try to defeat it.

''What kind of item is the reject crystal a haggle from?''
I don't understand it.
'What?　Why?
Because the rejected crystals themselves are an extinct species.

　An extinct species.
　It was the first word that came out of Antonio's mouth that he had heard since he came to this world.

'What do you mean by that?'
That's because they're a problem for adventurers. And depending on the point at which it exists, it's the only monster that will keep you out of the dungeon.
...... That's right.

　I remembered how hard it was to get that mansion.
　Me and Emily worked together, and on top of that, we finally defeated it with an ironclad bullet that defies all power vectors - what we called a scum bullet at the time.

　It's obvious that the average adventurer is going to be a handful.

The monster that was born after the Dungeon Master's rampage, it's said to have disappeared within a week due to its nasty nature.
Breed improvement.

　Antonio nodded clearly.
　It was too tricky, and they turned it off fast.

　It would have been a case that would have come to me if I was around then.
　That's fine, but an extinct species.

I don't know. ......

　　　　　★

　Cyclo at dusk. He goes home with Eli, holding hands with him.

　I went to Cell's place after that, but he said it was impossible for him to get it, too. But at Cell's place, I got some information.
　The reject crystal, the drop item is a fruit, durian.

　I'm not going to be the only one who can do this, but I'm not going to be the only one.
　I'm not sure if this is a tool-based drop, there's a possibility that there is one left, but the chances of it being a fruit drop are zero.

　Especially in this world.

　If it's the world you were in, there's a chance that there's rotten remnants of it, but in this world, if there's no one around the thing, it will hatch into something haggler. If it's a wreckage, it will be Frankenstein as garbage.

　The only possibility that the reject crystal durian is still around today is "someone who lives with a rotting durian around all the time".

　No such thing is possible.
　It's not zero in theory, but anyone can see that it's not possible.

'Oh, crap.'
......(?)

　I noticed that Eri was looking up at me with a blank stare.
　She looks slightly worried. It's probably because of the deep sigh I gave a deep sigh right before.

'Sorry Eri, I just sighed because it looks like I won't be able to get the reject crystal.
......

　Eri tilts his head, he doesn't seem to understand it well, so I explained it a bit more.

'That's the name of the monster, a monster with the ability to push every human out of its territory just by being there. That's what I wanted, though.

　What can we do without?
　So what should we do?

　Are we going to expand that house?

　Or do we build an extension and incorporate the erythronium dungeon in the garden?
　There's a dungeon in the mansion and a lair in the dungeon.

　That doesn't seem like a bad idea.

...... (gui)
Yeah, what's up, Eli?
...... (giggle)

　Eli grabbed my fingers and started walking away, pulling me along.
　I'd only just arrived right beside her before, but whatever she was thinking, she started leading me completely.

'Oh, hey. What's going on, Eri?

　Eli didn't answer and just went on.
　But it's Eri in her young form.
　I'm sure you'll be able to find a way to make the most of it.

　You'll be able to get a good idea of what you're looking for.

　Eli pulled me back to the mansion.
　I didn't go into the building, but went straight into the Erislonium dungeon.

　The Erislonium basement level, the place that is the entrance hall of the mansion.

　Eli took his hand away from me there and headed to the center of the hall.
　There, I closed my eyes and held out my hands.

　Light floods in and it gathers together to form a monster.
　It's the very monster I've seen so far, the very cotton wool of the erythronium - a monster.

Whoa!

　In a moment, a tremendous repulsion was applied to me.
　I couldn't hold on - in fact, I was blown away by the tremendous force.

　The next thing I knew, I found myself falling on my butt outside the dungeon.
　What's going on?

...... (smiling)

　Eli comes over to me at warp and hugs me and looks up at me.
　He's smiling, he looks like he wants a compliment.

'Did Eli make that?'
...... (nationally)

　Oh, I see.
　Eri, who heard the story from me, created a monster that mimics the characteristics of the Reject Crystal.

　A monster with the ability to eliminate foreign objects.
　If you think about it, I'm in good hands with Eri now.
　After all, the current momentum far exceeds that of the Reject Crystal.

''I see, thanks Eri.

　When I said that and patted her head, Eli looked extremely happy, and she hugged me and thrashed her cheek.

　It's cute and gratifying.
　I continued to nudge him for a while.

'Good. Eli, just wait here. I'm going to go beat that monster.
.......

　Eli was motivated.
　I guess that means he's going to beat me instead.

'Thanks, but I have to do this one. Will you support me instead?
...... (nationally)

　After convincing Eli, I entered the dungeon.

　As soon as I entered, the force to push out hit me.

　Refuse, the force to play is more than a reject crystal. As expected of Eri.

　But it's no problem.
　I'm stronger than I was then, too, and I know exactly what I have to do, so I'm thinking about countermeasures.

　The absolute rock stone, and ironclad bullets.

　I'm frozen stiff and invincible, and I grab the ironclad bullet I shot.

　An ironclad bullet is a slow-moving bullet that ignores all forces.
　It advanced normally without being defeated by the repulsive force of Eri's monsters.

　Besides, the stone of Absolute Rock froze me, grabbed me and pulled me forward by the ironclad bullets.

　The ironclad bullet can only advance a little.
　When it's about to disappear, I shoot a new ironclad and grab it.

　It's an ironclad relay.

　You shoot a bullet, grab it, and go forward.
　Before it's about to disappear, you shoot a new one and go further.

　I repeat the process and get to the fluff.
　I fired a series of ironclad bullets from zero distance, just to be sure.

　Poof!　And then the fluff popped and disappeared.

'Good!'

　I was gutted that we were able to take it down as per the simulation.