Main Scenario/Railway Above the Sea

The Dark Celestial Sphere Episode
30-1	Dark Celestial Sphere
30-2	Railway Above the Sea
30-3	Vortex of Ever-Darkness
30-4	The King's Ploy
30-5	St. Iris's Giant Tree
30-6	An Impossible Promise
30-7	The Five Altars
30-8	The Final Key
30-9	King of Ever-Darkness
30-10	Light Celestial Sphere
30-EP	Epilogue

At the Banská Mines, M. Flamarine, we obtained the last key - a blue stone.
With the help of Olivia the Kind, we hunted down Canaria at the altar, deeper than even the lower layers.
Canaria was turned into an incomplete monster by someone else. There was no way to save her, and Canaria met a horrific end when her body was torn apart and devoured swarms of Samanthas, but it cannot be said that the radical faction of the Resistance have completely stopped activities.
A stranger's voice spoke to Canaria at that time. Perhaps the owner of that voice was one of Canaria's comrades. There is no proof that the stranger is part of the radical faction, but the person is likely pulling Canaria's strings behind her.
But, now is not the time to deal with the Resistance. Shortly after obtaining the fourth key, the sea and sky of Iris Metro were enveloped in an evil darkness.
Islington	"Now now, we'll discuss about the blue stone we picked up on our latest cave expedition being the final key to rescuing the Guardians of the Giant Trees..."
Islington	"As soon as Banská's Mist subsided, an anomaly occurred in the M. Flamarine Sea. The Light Celestial Sphere, which produces blue skies, was covered by darkness and railway rails appeared on the sea."
Mary	"I guess you could call it the Dark Celestial Sphere."
Islington	"Oh, come on, that's not funny alright~? For the people of Metro, it's one of the biggest celestial spheres in the world."
Mary	"I'm not joking. If we let this go, the blue will disappear from the seas and skies of M. Flamarine."
Mary	"Look at those dark clouds. They are getting bigger in size. It's threatening to envelop every ball on the ceiling in darkness."
Islington	"I'm not even sure it's a cloud. Maybe it's a really bad Phantom Mist. You know, the one we saw when we first came to Metro?."
Mary	"Ever-Darkness."
Islington	"Yeah, that's the one. Is it anything like that Ever-Darkness?"
Mary	"That's true, if you ask me. If the King of Ever-Darkness is involved, it's possible..."
Islington	"This is really gonna suck~"
Mary	"Yeah, it would suck. The King of Ever-Darkness is not a monster born from Mist. On the contrary, he's a threat that didn't even exist in Iris Cloud."
Paddington	"If the King of Ever-Darkness was involved in that celestial sphere, then how can we free the Guardians of the Giant Trees?"
Mary	"That's still not uncertain."
Islington	"Defeat the King of Ever-Darkness. That's an answer I don't want to utter."
Mary	"We've seen the power of that thing up close. If the Conductor's magic works, we may have a chance."
Paddington	"And what if it doesn't?"
Islington	"It means the Iridescent God's power won't work."
Paddington	"That means..."
Islington	"Mhm. It means that the harmony of this world will not be maintained."
Islington	"Welp, if he was such a powerful king, Iris Cloud and Iris Metro wouldn't be safe now. The fact that this evil king has kept quiet until now means that there are ways to contain or inhibit his power."
Paddington	"......"
Islington	"Please, sis. Don't look at me like that. A Divine Child must always be positive. That's what Mr. Conductor wants to say."
Paddington	"What are we going to do now? The Dark Celestial Sphere is growing in strength as we speak."
Islington	"There's no time to go back to Iris Cloud. The SSS will continue by train to the Celestial Sphere. That's the way the Metro railways are built, it seems."
Mary	"It can't just be a coincidence that there's an island just below the celestial sphere. That island is the end of the ocean railway. So, if we have a train, we can get there."
Islington	"That's what I mean. Things are going well. Former Knight Commander. Except that the enemy looks strong."
Islington	"We're not jumping into any enemy traps. We are going to the source of the Mist that must be cleared by the guidance of the Giant Tree and the Iridescent God. The missing guardians will be in that celestial sphere in all likelihood."
Islington	"...That's your battlefield. Fight to the death and win."
Mary	"As you wish."
Islington	"Mr. Conductor, Paddington, please. This is another deadly mission. Take only the strongest soldiers you can find."
Paddington	"What about you, big sis?"
Islington	"I'll protect the land. I've already fortified the coastal defences. The M. Flamarine Navy will cover us at sea. I told them it was dangerous, but they wouldn't let me go."
Mary	"The navies of each country are well trained because each of them has subterranean seas. Yes, it's dangerous, but it's better to have backup."
Islington	"Come on, Mr. Conductor, the SSS is in full swing. The target is the Dark Celestial Sphere. We're going to run the train to that island, which is clearly in trouble."
Thus, we crossed the rails that appeared in the M. Flamarine Sea and set out for an isolated island just below the Dark Celestial Sphere, off the coast of the dark seas.
Originally called the Light Celestial Sphere, the celestial sphere that creates sunlight and blue skies is now shrouded in deep darkness...
Yakutsk	"I never thought I'd end up on a Mist Train over the sea."
Queensway	"If you're saying that this rail appeared because we cleared the Mist from the Banská Mines, then it must mean that the Ruins of Thunder have something to do with the ancient railway.'
Yakutsk	"The Ruins of Thunder had an altar like the one at Banská."
Mary	"If the Ruins of Thunder and the altar have something to do with ancient railways, then Iris Metro's celestial sphere may also have some influence on such ancient railways."
Queensway	"Artifacts from the same period, you mean?"
Mary	"I can't say for sure, but it's not impossible. At the very least, it seems different in nature from the Poisons from the otherworlds."
Yoshino	"Seems like both the railway and the celestial sphere are things that are there to deal with the Poison from the otherworlds."
Yakutsk	"Right now, I think the celestial sphere is going to do something to this world."
Yoshino	"Pretty sure those black clouds are not created by the celestial sphere. If we can defeat the bad guys who turned it into the Dark Celestial Sphere, it will return back as the Light Celestial Sphere."
Mary	"It depends on who the bad guy is. Hopefully it will be a small villain like Canaria."
Queensway	"I'm sorry to hear about Canaria. I wish there was a way to save her..."
Mary	"Yeah, it's a real shame. I'm sure Yuuzen feels the same way."
Mary	"She loved Canaria so much..."
Queensway	"Mary, did you say something?"
Mary	"No. Nothing."

The Dark Celestial Sphere Episode
30-1	Dark Celestial Sphere
30-2	Railway Above the Sea
30-3	Vortex of Ever-Darkness
30-4	The King's Ploy
30-5	St. Iris's Giant Tree
30-6	An Impossible Promise
30-7	The Five Altars
30-8	The Final Key
30-9	King of Ever-Darkness
30-10	Light Celestial Sphere
30-EP	Epilogue