Main Scenario/Part of the Railway

Ruins of Thunder Episode
27-1	Song of Doom
27-2	Joint Operations
27-3	A Strong Tribe?
27-4	Intuition of the Shana Tribe
27-5	Ruins of Thunder
27-6	Mysterious Sealed Wall
27-7	Part of the Railway
27-8	A Small Handprint
27-9	Princess of Thunder
27-10	Mission Accomplished

When the mysterious seal found on the wall of the Metro Hole was broken, ancient ruins were spread out beyond it.
Whether these ruins are 'Ruins of Thunder' or not remains to be seen, but the atmosphere is somehow different from the ancient ruins found in the Verforench forest. From the fact that the shana's deciphering skills were required, it is almost certain that these ruins are related to the shana people in some way.
The problem is that Iris Cloud monsters were mixed in with these ruins, which exists in the Iris Metro universe.
Versailles	"It's cornered. This is a dead end. There's nowhere to run now."
Monster	"......"
Versailles	"It's gone?"
Queensway	"Surely it wasn't a special type of monster that disappears, right? It's one thing if it disappears into the Mist, but to suddenly disappear right in front of us..."
Queensway	"?"
Queensway	"Wasn't there only one Mist Monster? We haven't seen any Phantom Mist since we discovered it until now. Where is the source of the Mist?"
Versailles	"If it was a demon that emerged from the Mist generated by Iris Cloud, isn't it possible that it left the source and melded in here?"
Brittany	"I think that is highly unlikely. The Phantom Mist that appeared in Brocéliande wasn't much of a threat. If there were more than one monster as big as the one we saw earlier, there would have been more commotion."
Queensway	"Then does that mean that the source of the Phantom Mist is somewhere in these ruins? In that case, the monster we saw earlier are outsiders just like us?"
Yoshino	What if we change our assumption that 'monsters flowed into the subterranean from the surface'?"
Yoshino	"What if we did not use the railways to go between the surface and the underground?"
Yakutsk	"That's impossible. Even if there were other ways, there is no faster way to travel than by train.
Yoshino	"There are many ways to get around. Maybe it's not even 'travel' in the first place."
Yoshino	"Did all of the Phantom Mist travel into the ruins?"
Yakutsk	"?"
Yakutsk	"I don't understand a word you're saying, as usual."
*BANG*
Versailles	"All the lights have gone out at once!"
Queensway	"And what was that loud noise? It was coming from behind us!"
Finchley	"Everyone on the alert! It's a trap!"
Versailles	"Trap!?"
Queensway	"Is it Mist!? How many enemies?"
Finchley	"Calm down. There is no Mist. But our rear has been walled shut."
Euston	"Have we nowhere to run?"
Versailles	"Was the demon I saw earlier a trap? It was meant to lure trespassers into this room..."
Versailles	"If so, it is my fault. Because I inadvertently chased after the demon."
Euston	"It's not your fault that we all chased the demons."
Versailles	"But..."
Queensway	"Also that monster is an Iris Cloud Mist Monster. It's true that there were traps set in these ruins, but it's hard to imagine that the monster we saw earlier had anything to do with it - we would have been trapped here even if you hadn't gone after it, Versailles."
Versailles	"Miss Queensway..."
Brittany	"The lights are back on?'
Vivienne	"Let's make sure everyone's safe. Is anyone feeling unwell or injured?"
Putra	"It looks fine, but look behind us. We're not going to get back on the train."
Looking backwards, we saw a huge wall blocking the path we had just taken. It's troubling that the wall appeared rather than being formed by the ceiling collapsing. If it was man-made, it might be difficult to destroy with magic.
Vivienne	"There's a gap just wide enough for the rails to go through. Why on earth would that be? Are you saying that the rail's magic is part of the trap's setup?"
Yoshino	"The trap was designed to fit there from the start. It's not that the rail bounced off the wall, it's an artificial trap made to avoid the rail."
Yoshino	"This is very interesting. Makes my 'kougyoukei' blood boil."
Yakutsk	"It's not the kind of trap that can be made with just your ironworking skills. Do you think you can disarm this trap with just the tools you have on hand?"
Yoshino	"Don't think so. Yoshino however, is surprised that these ruins are 'part of the railway'."
Yakutsk	"Part of the railway?"
Yakutsk	"......"
Yakutsk	(What do you mean?)
Yoshino	"Maa, Yoshino'll just say this much and is sure Queensway and others will understand."
Queensway	"Part of the railway... I see! That's what it means!"
Queensway	"If this contraption was built with the rails in mind, wouldn't there be railway rails running through this whole site?"
Queensway	"Just like the halt where we stopped the train, wouldn't these ruins have been part of the railway line leading from the Metro Hole since eons ago?"
Euston	"That would certainly be interesting."
Euston	"Perhaps what my sister was after were railway-related sites and ruins such as this one..."
Finchley	"You have a sister, Euston?"
Euston	"Yes, well. She used to survey sites a lot back in the old days."
Euston	"These ruins are definitely the Ruins of Thunder in the village of the shana people. It is similar in construction to the altar room used by the Shana in their ceremonies. Don't you agree Versailles?"
Versailles	"Yes. I also think this is the Ruins of Thunder. It's a bit different from the surface ruins, but all the underground passages and halls are like this."
Queensway	"Then maybe you know how to disarm the traps? Maybe if you and Miss Brittany work together, you can disarm it like you did earlier."
Versailles	"I think it would be difficult. The Ruins of Thunder that I know of did not have traps like this to prevent intruders."
Versailles	"This is a section that has never been entered by the modern shana tribe. This is further back in the altar room, a secret place sealed off in the past by the ancient shana."
Euston	"There must be a reason for the secrecy. Either there was something hidden that they didn't want to be seen, or they needed to lock something away..."

Ruins of Thunder Episode
27-1	Song of Doom
27-2	Joint Operations
27-3	A Strong Tribe?
27-4	Intuition of the Shana Tribe
27-5	Ruins of Thunder
27-6	Mysterious Sealed Wall
27-7	Part of the Railway
27-8	A Small Handprint
27-9	Princess of Thunder
27-10	Mission Accomplished