After defeating the Giant Octopus and passing through the Demon Sea, the voyage was smooth.

　After half a day of sailing from the time we boarded the pirate ship at the marina, the ship finally arrived at our destination.

　It was late afternoon, just before dusk.
　Under the mild afternoon sun, the boat arrives at an island.

　But it's not just a sandy beach that the ship has arrived at.

　It was inside a large sea-eroded cave at the bottom of a sheer rocky cliff.
　The topography of the cave is similar to that of a sea god's dwelling place.

"All right, we'll stay here. Be careful not to crash the boat into the reef.

　At the dead end of the sea cave, Marina instructed the sailors to anchor the ship.

　Incidentally, Marina seemed to have decided to force her way into the "demon sea" over the objections of the sailors, but even though this led to an encounter with the Giant Octopus, the "Sea Devil", the sailors of the pirate ship did not defect from Marina.

　After we defeated the Giant Octopus, Marina strutted her stuff in front of the crew and dared them to "boil or burn me if you don't think I'm worthy of being captain," but none of the crew tried to harm her.

　I would have kept my mouth shut if things had gotten out of hand, but I was glad to see that there were no problems.
　I guess Marina is more trusted than I thought by the crew of this pirate ship.

　Anyway, the ship anchored at the end of the sea cave.

　A group of brave men jumped down to the ledge beside it.
　It was me, my students, Anya, and Marina.

Alright, we're going to go find Captain Mithril's treasure. You guys take care of the ship.

"Yes, sir!　Have a good day, Miss!

　The sailors shouted a spirited farewell in thick voices.

　The two strong male heroes were to remain on the ship to guard the other sailors.
　I guess it was an unavoidable decision, since the movements of Sahagin and his men were unpredictable.

　So, Marina, myself, my students, and Anya, a total of six heroes, started Captain Mithril's treasure hunt.

　Well, to be honest, we didn't really have much motivation to participate in the treasure hunt.

　In any case, we didn't have a clue until we encountered Sahagin, so we were hopeful that we might make some progress if we proceeded.

　We stepped out from the ledge beside the anchored ship and into the narrow cave that led beyond.
　In my hand, I held a light prepared with the magic of [Light].

　As I followed Marina down the narrow path, which was barely wide enough for one person to fit through, I observed the surrounding rock formations.

This cave has clearly been touched by human hands. Maybe they used some kind of tunneling magic to dig it up.

So, Brett, this cave on this island is definitely the perfect place to hide Captain Mithril's treasure, right?

Yes, it is. Anya, Anya, watch your step.

Yes, I'm fine. Thank you, Mr. Brett.

Anya, I'm telling you right now, you can't fall in love with my brother. He's already overbooked.

Mmm. Why is it that I always find myself surrounded by women?

...... Iris, it's probably not worth thinking about. ...... Your brother is like a magnet.

　I'm not sure what to say.
　I'm not sure if I'm going to be able to do it.

　Incidentally, there were many things that I wanted to say about the three students, but there was no end to it, so I'll leave it at that for now.

　After a while of stooping and walking through the narrow cave, we eventually came to a large open room.

　It is still a cave, but the ceiling is high and the surroundings are wide.
　The atmosphere could be described as a hall.

　In one corner of the hall, there was a large stone door.
　On the wall beside it, there was a stone monument with some kind of writing on it.

　Curious, Maifa walked up to it and read out what was written on the stone monument.

...... What's that? ...... "My brother's mornings are early. Every morning he steals our underwear while we are asleep in bed. He does it all the time. He replaces the new underwear with used underwear...' Ouch, ouch!　Give it up!　Give up ......!

　I walked up behind Maifa and did my customary head-butting.

You're not writing this down, are you, hmm?　I'm not sure if I'm going to be able to do this, but I'm sure I'll be able to do it.

"......Ugh ...... I was just kidding ....... ...... your brother's tweets have been more intense lately ......

I don't know. ...... d*mn.

　I regained my composure and read out the words on the stone monument.
　It read as follows.

I'm sure you'll be able to understand why I've been so impressed with your work. Those who do not have the two keys may leave.

　I tried to read it out loud, but to be honest, I didn't understand a word of it.

　I looked at the door and the surrounding area, but could not find anything that looked like a keyhole.
　On the contrary, the stone door was almost completely flat, with only a single handle on it.

"What's that, 'qualification'?　Two keys?　I only have a map...

　As Marina muttered to herself, she tried to put more pressure on the stone door.
　And then...

　Gogo gogo gogo.

　The large stone door, while making a heavy sound, opened straightforwardly.

...... What is it?　It opened just like normal.



"So, is there a trap up ahead?　Like, if you don't open it the right way, the trap will trigger and hurt you.

Haha. Even if that's the case, I'd be out of the pirate business by now if I were to get scared and leave here.

　I'm not sure what to make of it, but I'm sure it's worth it.
　I'm not sure what to make of that.

　...... It's good that she's brave, but she's the kind of girl who's going to die before long.
　If you can survive, you may become a very strong and brave person in the future.

　However, Marina seems to have her own style and determination, so I don't think it's something I should be teaching her right now.

It's not like I can't teach her anything now. There are no traps, and the road continues as usual.

　I'm not sure if this is a good idea, but it's a good idea.

　If there is nothing to ...... be found, is the content of this monument fake?

　I'm not sure that anyone who would go to the trouble of building a place like this to hide treasure would do such a thing.

　But maybe the message is not about how to open the door, but about the whole hiding place of the treasure.

　In any case, as long as we don't know the meaning of the words written on this stone monument, all we can do is choose to move forward or retreat.

　Considering the strength of our forces, I don't think there's much danger unless...

"Hmm, ...... brother, what should we do?

Honestly, I don't know the right answer. What do you and Rio want to do?

　When I asked that back, Rio, Iris and Maifa looked at each other.
　They nodded at each other and said.

"I want to go!

"I'd like to go, sir.

...... Curiosity kills the cat. ...... But boredom kills. ...... I feel like a cat right now.

　And all three of them seemed to be on board.
　But I think Maifa's is going to die.

"What about Anya?　We can wait on the ship if you want.

　When I asked the last one, Anya made a little thoughtful gesture, then replied.

You're going, aren't you, Brett?　So am I. I'm a little concerned about something.

"Okay, okay. All right, let's go treasure hunting together.

　And so, we stepped through the great door and beyond.

　Now, will there be an Ogre or a Python?

　It's been a while since I've done any real dungeon exploration, so I was also a little excited, even if I was a little old for it.