Haruto Saito continued diving deeper into the ocean.
The further he went, the darker it became. Eventually, he could no longer see his own hand in front of him. Even in the clearest waters, sunlight could only penetrate up to two hundred meters below the surface. Beyond that, there was nothing but total darkness.
The pressure increased with every meter he descended.
Haruto felt his lungs being compressed.
It was said that when a human dove deeper than a hundred meters on a single breath, their lungs would shrink to the size of a fist. Conversely, if they ascended too quickly from that depth, their lungs could expand and even burst.
This was due to the immense underwater pressure.
A balloon released at a hundred meters below the surface would rise rapidly, and as it ascended, the decreasing external pressure would cause it to expand until it exploded.
For an ordinary person, rapidly surfacing from just fifteen meters below could result in a fatal lung rupture. If they controlled their exhalation, they might avoid death, but the damage to their lungs would still be severe.
Of course, none of this was a concern for Haruto.
He was no ordinary person—he was a shinobi, and one with enhanced physical endurance from rigorous taijutsu training. His lungs would not rupture, though he still had to endure the increasing pressure.
He soon reached two hundred meters.
Darkness surrounded him.
Even bioluminescent fish were absent.
Although he had night vision, it still required some level of ambient light.
Haruto retrieved a glowing pearl from his storage space.
Even with this light source, he could only see about thirty meters ahead—beyond that, visibility was nonexistent.
But it didn't matter.
Haruto continued descending.
Three hundred meters.
Four hundred.
Five hundred.
...
Eight hundred.
...
One thousand.
The depth was astonishing.
Haruto finally understood why the Edo treasure had remained undiscovered for over six centuries. If this really was the legendary Edo treasure, then its location alone explained everything—this part of the ocean was terrifyingly deep. Even with advanced diving equipment, ordinary people could never reach this depth. Their bodies simply wouldn't survive the pressure.
Even most shinobi and samurai, unless they possessed extraordinary physiques, would be incapable of diving this far.
Haruto himself was starting to feel discomfort.
Still, he pressed on.
He encountered bizarre deep-sea creatures—some luminous, some grotesque. Schools of glowing fish surrounded him, painting the darkness in a kaleidoscope of colors.
"I really hope I don't run into some kind of deep-sea monster," Haruto thought.
After all, this was the world of shinobi, where legendary creatures known as summoning beasts existed. If there were an underwater equivalent of those beasts, it would be a nightmare.
Haruto finally reached fifteen hundred meters.
And there it was.
A sunken ship.
It was exactly as the treasure card had guided him.
The ship had long since decayed, with corals and marine life growing on its surface. Despite its deteriorated state, it was massive—easily a hundred meters long. Some of it was buried under silt, making its exact dimensions unclear.
The hull bore numerous dents and fractures from past attacks.
"The ship of the Edo royal family?" Haruto wondered. He wasn't sure yet.
Still, a ship of this magnitude was extremely rare six hundred years ago. Even in the present day, such vessels were uncommon. Any faction capable of constructing something like this must have been formidable.
Haruto swam inside the wreckage.
A school of fish darted out, startled by his presence—some even colliding with him before dispersing.
He began searching.
Looking for valuables.
After just a few meters, he found a lantern stand that appeared to be made of solid gold.
He took it.
He continued searching.
One by one, he collected over twenty pieces of gold and silver artifacts. Then, on one of the doors in the ship, he spotted engravings—symbols he didn't recognize, but also characters he could read.
It said "Edo."
That confirmed it.
This was indeed the Edo treasure.
Haruto pressed on.
His head started to feel light, and the sensation intensified.
It wasn't just the pressure—he was running out of oxygen. He had been holding his breath since he first dove down.
"Do I need to surface already?" he thought.
That would be a hassle.
Going back and forth would take too much time. Who knew how many trips he would need to thoroughly search the entire ship?
"Maybe I can use a card?"
Haruto retrieved a basic healing card and consumed it.
A refreshing sensation spread through his body.
It worked!
His mind instantly cleared. He quickly realized why—it wasn't just healing his body, it was also replenishing his oxygen levels. Since oxygen was essential for bodily functions, the healing effect had restored it as well.
That meant he could keep going.
He resumed his search.
There were many small chambers, their doors left open. In nearly every room, he found gold and silver valuables. He meticulously scoured every corner—one level, then the next, then the next.
On the third level, he found the ship's storage room.
It was enormous. Inside, numerous fully sealed chests had tumbled into a massive pile due to the ship's tilted state.
Haruto opened a single chest.
It was filled with gold ingots.
He didn't need to check the rest—he knew they contained the same.
Without hesitation, he stored every chest into his inventory space. The final count was eighty-seven chests.
But he wasn't done yet.
Haruto kept searching.
Soon, he found even more valuables in various rooms.
Curiously, he had yet to encounter any skeletal remains. Not a single corpse.
There were two possible explanations. First, when the ship sank, most of its passengers likely tried to escape by jumping overboard rather than going down with the vessel. Second, even if they had sunk with the ship, after six centuries, their bodies would have been entirely consumed by marine life—perhaps even their bones had vanished.
Haruto continued exploring.
He reached the ship's stern, where he found the last chamber on the third level.
The door was shut.
He kicked it open.
Inside was a small, square room, overgrown with aquatic plants. However, amidst the tangled vegetation, Haruto spotted something unusual.
A skeleton.
Clothed bones, clearly belonging to an adult male. The corpse's fingers were adorned with numerous rings. In its left hand, it clutched a sheathed katana.
"Could this be…the king of Edo? The leader of the Edo clan?" Haruto speculated.
It wasn't just an idle guess.
The skeleton wore a crown.
Haruto swam closer, intent on looting the body.
Just as his fingers were about to touch the crown—
The empty eye sockets of the skull suddenly flared with a ghastly green light.