There is endless darkness outside the acrylic glass.

Deep sea night——

Almost breathless silence and cold seeped into the skin through the carbon alloy hull.

The floodlights reflected only the remains of plankton falling like snowflakes. The investigation submarine "isrus" is continuing to dive towards the seabed inaccessible to the sun.

"What's the depth of the dive?"

The captain in a blue submarine suit asked in an impatient tone. Subordinate to the folk diving investigation company, he is an old hand with nearly ten years of diving experience. The man who used to be joking and cheerful is very unhappy today. He is full of anger that wants to kill.

Seems to feel helpless about the captain's attitude, replied the young pilot.

"It's over 4000 meters and 2500 meters from the submarine limit"

"... did you really sink to such a place? That thing?"

The captain snorted unhappily.

The deepest sea area in the east of XianShen Island, which they were entrusted to investigate, has a water depth of more than nine kilometers. Nowadays, only a handful of submarines can dive to that depth. In other words, it is the forbidden field for mankind.

"Biological weapons of the mythical age... It is said that the wreckage of that thing can be found nearby. Where are all these rumors? It is estimated that it is some groundless legend or the like?"

"Who knows. Maybe it's a half fish man or something?"

"... halffish man?"

"Ha ha, just kidding. But the client this time is an enterprise of the 'demon special zone'? Then it's not surprising to know people in this field."

"Really. Then why don't you just hand over this boring investigation to those guys?"

The captain said in disgust and sighed deeply.

It is said that the traces of biological weapons made in ancient times - this is the search object of "islus". This stupid job is the reason why the captain is unhappy.

In other words, the purpose of building the submarine "islus" was to investigate and study the ecosystem and evolution of deep-sea organisms. It is obviously not its original task to explore antiques whose existence is uncertain.

"Anyway, I still don't think it's worth spending so much money to find it. Isn't it rumored that the ancient weapons (narakwala) left by those people in the 'Ministry of heaven' were easily destroyed by the SAR police?"

"Do you mean the thing that the Black Death emperor sect brought to Xianshen island? Well, speaking of rumors, there is another saying that the fourth Zhenzu actually destroyed it... If it's true, it's better not to underestimate the ancient weapons... Huh?"

The driver who had been observing the exploration display suddenly frowned in doubt.

The captain looked at him with a surprised expression.

"What's the matter?"

"It's different from the terrain data... This is it. Can you see it?"

The screen pointed by the driver shows the seabed terrain after CG processing. The 3D image reproduces the terrain data obtained from the past survey. The image displayed with frame lines is the real-time situation obtained by the sonar of "isrus". There is a strange dislocation between the two data that should be completely consistent.

There is an area at the bottom of the sea that spans several kilometers and rises slightly upward.

"It seems that the sonar is not affected by the variable temperature layer. Is it the abnormal uplift of the seabed?"

"No... there is no sign of volcanic activity in this sea area. This shape... It's like some creature..."

"Biology?"

How could it be - the captain stared at the pilot's pale side face and exclaimed. However, the analytic picture of Sonar on the screen is changing its shape irregularly bit by bit.

It does look like a creature crawling on the bottom of the sea.

A crocodile or snake with a length of several kilometers - or maybe a giant dragon.

"How could this creature exist... It's too big... It's just... It's really a monster in myth...!"

The captain wanted to convince himself, but the pilot beside him suddenly screamed.

Then a torrent like an explosion hit the submarine in an instant.

It was a strong deep sea wave with a water pressure of 4000 meters below sea level——

The violent whirlpool near the bottom of the sea rolled the "isrus" like a leaf. The pressure housing protecting the driver's seat is strongly squeezed and makes a moaning sound.

The source of the vortex is obvious without confirmation. It's a monster. The huge monster sinking at the bottom of the sea moved slightly. This alone creates a strong shock wave around.

"Sure... Confirmed the pulse wave of biological magic! This guy... Is alive...!"

The driver grabbed the seat and shouted.

A giant sea creature with a total length of several kilometers. This is beyond common sense and absurd existence. Now, however, it has actually appeared in front of them, bringing overwhelming destruction and fear.

"Avoid...! emergency avoid! Go up!"

The captain screamed. But the hull of "islus" rolled violently in the sea, and even the sense of direction up and down disappeared. The ballast for emergency buoyancy has been disengaged, but it has little effect in the turbulent vortex.

At the next moment, as if caught by some huge object, "isrus" stopped.

The hull broke apart in the terrible shock. The pressure housing also makes a strange sound.

"Over, over the pressure limit! The ship is going to be crushed -"

"At this depth...!"

The captain held his breath in the pilot's wail. Even in this situation, there is still room for the submarine limit of "islus". In particular, the special pressure shell is made to bear the hardness of 10000 meters of underwater water pressure because of the safety of passengers. Such a strong "isrus" is being crushed by a great force.

"Boat, Captain!"

"Is it..."

The floodlights that provided illumination outside the ship had been damaged and the surrounding was in darkness. The last light that appeared before this was countless sharp teeth like rocks——

It was the jaw of the giant monster that caught the submarine "isrus".

"Are we... Being eaten...!?"

The captain whispered in amazement.

Before they finished, the pressure shell of "islus" broke apart, and they didn't even have time to feel the cold of the sea, and their consciousness sank into endless darkness.