Defense specialization and crack three.

The two move through the water, the scenery unchanged as ever. Midway, their oxygen replenished, they have explored a range far wider than initially anticipated.

How long have we been swimming?

According to the map, we’re just reaching the center of the crack. We’ve been going nearly straight. Many areas—edges, the opposite wall—remain unexamined.

Until now, it was impossible to know. The seabed consists of various terrains joined together. Different regions, like the rocky zones and sandy stretches they’ve passed, each have distinct features.

The sandy areas seem to be ambush-focused, like the last one. If the object we seek exists, it’s likely elsewhere.

There’s nothing but sand.

It could be buried. But that would be impossible to search.

Digging through this vast expanse of sand without markers or proof is impractical. Proving something does not exist is difficult. It would go on endlessly.

“Monsters we can handle!”

“Let’s just get out quickly. Once we know the seed’s location, surprise attacks from below won’t matter. We don’t need experience or loot.”

Having no purpose in the sandy area, the two fought off monsters rising from beneath their feet and pressed on until the sand ended. The headlamp ahead now revealed a surface that looked like solid rock.

“Again, rocky?”

“From the map, we didn’t backtrack incorrectly. This place is different. Besides, there are no tall rocks like before.”

“True. That’s right.”

“Harder to hide, too. The earlier ones definitely aren’t here… unless, of course, the difficulty level has increased.”

Hiding places are few here—this will be difficult...

Perhaps we should proceed with caution. The oxygen levels are dropping again.

"That's right! If we linger, we'll lose the chance to explore!"

Even with excessive caution, there was no help for it. The two swam onward into a new area. Among the jagged rocks, they discovered fragments that resembled stone bricks, though broken and worn.

"Sally, Sally! What's wrong!?"

What could possibly lie submerged here? No need to spend much time exploring this area. Even if the journey grows long, little will be gained.

"Salute!"

I’ll stay by Maple’s side until we know what monsters might still be here.

It’s fine! I’ll do my best to protect you—

I am waiting.

As the two continued their search for further clues, they discovered multiple traces of past human presence. Though worn thin, structures made of sturdy materials still retained enough form to be recognizable.

"Over here, Sally!"

"The number of fallen items is increasing. I think we're getting closer to the center of this area."

Progress was favorable. Maple swam back and forth, steady and sure. Then, suddenly, as she directed her headlamp forward, the place emerged from the darkness.

"There's a building!"

"Though ruined... it's definitely a structure. A town, perhaps?"

This had once been the entrance to the town. She shifted the light’s angle. Most buildings had collapsed. Only a few shapes remained recognizable. The sheer volume of rubble, however, spoke of a town of considerable size.

"Let’s go in!"

"Yeah. No sign of monsters."

There was no reason not to enter after coming this far. The town offered more cover than the sandy area. They would move through it carefully, alert for ambush.

"Any buildings we can get into?"

"Can’t search under the rubble. That’s likely where the real treasure lies."

"Fufu, I’ve gotten good at exploring ruins!"

"Really? Seriously?"

"W-well, I’m not sure… but I’ve done it quite a bit!"

"Yeah. You’ve explored more than ever before. You might even sense something worth finding."

Sally lets Maple take the lead, trusting her instinct.

Maple moves with clear purpose, stepping first into a nearby building.

She checks ruins—doors, furniture, even homes with no roofs—but finds nothing inside.

Most things bear the marks of the flood’s violent destruction.

“Mmm, nothing here…”

“Next one.”

“Yeah, let’s keep going!”

Even if nothing turns up after a few tries, they do not give up. They stop only when they have searched thoroughly and found nothing.

Sally follows closely behind Maple, who moves with energy, checking for anything overlooked.

They came this far—something must be brought back. For Maple’s sake, certainly, and for her own as well.

They swam in circles, but the monster seemed absent. Then, keeping a measured distance between them, they advanced their search with efficiency. The range remained such that light from their headlamps still reached, and voices carried clearly.

Maple! Something wrong?

Found it—!

Yes... it was... there!?

Sally nearly let the words pass without response, but turned toward Maple, using the headlight's beam as a guide.

And what happened?

Ah, Sally, this, this!

This... a stone monument? It does not seem merely a stone.

The stone monument, caught beneath a collapse of nearby debris, is the same deep, dark black as the surrounding water, radiating an atmosphere distinct from the stone and iron scattered around it.

“Then, something is written here… this.”

Perhaps it's writing...

Not all are perfectly preserved—some are worn down by rubble—but the surface of the black stone tablet bears characters that resemble those taught to Kanade, just slightly.

“Sally, can you read this?”

“No… well, maybe a little. Mostly I don’t understand.”

“I only learned it back then… ugh, the number of lessons….”

They are not foolish, but suddenly memorizing an unknown language is beyond them.

Only Kanade could manage something like that.

“…………”

They exchange glances. There is nothing else to do. They open the window and begin typing a message.

After a short wait, a reply arrives from Kanade, the intended recipient.

Interesting thing found, it seems. Still difficult to read, so I’ll lend a hand. Fill in the gaps and translate what’s missing. Something’s located in the center of Town. Said to be something important, sealed and guarded with great care. Shall we go take a look? I look forward to hearing about your adventure.

“Quick reply—helps a lot… So, a seal, is it?”

“What could it be?”

If whatever lies sealed is of consequence, combat may be unavoidable. Then the remaining oxygen becomes vital.

“Maple, can you fight?”

“Skills are fully charged! I think I can manage the oxygen!”

“Then let’s head straight to the center. Tell Kanade our thanks… Good.”

Destination settled, the course shifts toward the center of Town. Exploration of the surroundings is set aside for now.

Having originally ventured deep into the Town, they reached what appeared to be the center without delay.

"Is this it?"

"Likely."

A building made of the same black stone stood there. Yet it had been sealed tightly since long before the stone monument was erected. The door, warped and hanging by a thread, had been damaged when the water overflowed. It no longer served as a door. A gap remained. They could peer inside.

"Appearance suggests no great space within. Shall we enter?"

"Monsters here are large. Such a small space wouldn't suit them."

They entered without hesitation. No ambush awaited. As expected, nothing stirred. Silence enveloped the interior.

The depth measures around five or six meters. No traps are visible.

Only a pedestal and the characters inscribed upon it remain, seen by circling the interior along the walls.

……Uwa.

Kuu, help me, Kanade!

There is no way to catch up with the impromptu lesson now. The only option is to call the teacher.

Kanade had anticipated that the writing would appear in only one place.

She expected that, for a time, more messages might come from the two others. The reply came without delay.

Eh, so we must apply the elemental magic corresponding to each wall? But!

It says just that here. I’ll handle it. Maple does not possess that kind of magic.

Maple can only properly wield poison magic. She cannot resolve this mechanism. An item might satisfy the condition, but Sally is here. There is no need to consider it.

Sally can use any magic without issue. It is sufficient to solve the mechanism.

“Fireball!”

Sally prepares the spell and releases it toward the wall. It strikes the wall and explodes instantly, vanishing to reveal a crimson magical circle floating in the air.

“Ooh! Did we succeed?”

“Seems so. Let’s try the others.”

Sally directs the spell toward the remaining walls. There is no hesitation. The attributes corresponding to each wall have already been deciphered, thanks to Kanade.

The magic circles rise above all the walls. A crack splits the black pedestal before them, splitting into two, and a sphere bursts at the center. The light flashes like electricity—sharp, violent—radiating intense energy. Yet nothing more occurs.

...Nothing happens. Shall we touch it?

It’s buzzing terribly...?

I’ll activate 【Pierce Guard】 just in case. I’ll be ready to heal at a moment’s notice.

Got it! I’ll try it!

With 【Unyielding Guardian】 still active, even in the worst case, they will not fall before disengaging.

Maple activates her skill as promised and touches the sphere. Immediately, a magic circle of the same color unfolds upon the ground, and a fierce light erupts from beneath their feet.

—【Cover】!

Maple shields Sally at once. Both vanish into the light.