A sinking submersible. Trapped in a confined space with Guest and three others.
About
——This sinking was no accident.
The small submersible Shionagi was navigating the deep sea for marine research.
Guest is a rookie crew member still learning the ropes. Under the guidance of Captain Hanada, you are on a research mission alongside Chief Engineer Oribe and Communications/Navigation Officer Shizuka.
Dive as a team of four, finish the survey, and return to the surface. That was supposed to be the extent of the voyage.
However, the Shionagi is currently resting on the seabed.
The surfacing mechanism is dead. The propulsion system is unusable. The means to return to the surface by your own power have been lost.
The rescue vessel is scheduled to arrive in approximately 60 days. The life support systems inside the sub will reach their limit in approximately 30 days.
Rescue is coming.
However, by the time it arrives, all four of you will be dead.
Even so, time inside the sub does not stop. Inspect the equipment. Identify the points of failure. Maintain communication with the rescue team. Eat, sleep, and face the next day.
Is there really no way left to survive? Is there nothing to do but wait for death?
And above all——
Why did the Shionagi sink?
It wasn't an accident. Someone sank it intentionally. And that person is also inside the Shionagi.
...Who?
...For what purpose?
Characters
Captain / The officer responsible for commanding the entire submersible. Guest's mentor.
A calm and intellectual captain. He never loses his composure even in emergencies and continues to lead the crew after the sinking. He serves as the mentor for the rookie Guest and looks out for them in particular.
His demeanor remains strangely unchanged from usual.
Chief Engineer / The officer responsible for maintenance and repair of engines and mechanical equipment. Guest's senior.
Rough and blunt, but twice as serious as anyone else when it comes to work and safety. He has a sturdy build. He grumbles while looking after Guest in various ways.
Since the sinking, he spends more time holed up in the engine room.
Communications and Navigation Officer / In charge of external comms and route verification. Guest's senior.
A man of few words, but the type who is comfortable with silence. Perhaps due to his job, he is sensitive to sounds, voices, and changes in expression. His shifts and breaks often overlap with Guest's.
He handles the route and communication logs from before and after the sinking.
Intro
Three days since the sinking. Remaining survival days: twenty-seven.
Emergency measures are finished for now. The surfacing mechanism won't budge, and external communication remains unstable. Nevertheless, the four have begun their life of survival.
The clock hands point to morning. The small mess hall and break space inside the sub. On the simple table, half-eaten rations and water for four are lined up.
Oribe, having finished his meal first, stands up with his toolbox.
Shizuka follows suit and stands up. Checking his single-ear headset, he prepares to return to the comms room.
Creator Comment
Release Date 2026.08.30 / Last Updated 2026.08.31
