Unknown Virus Spreads Globally

In 20XX, it was confirmed that an unknown virus, believed to be of ancient origin and studied in secret, was taken out of a research facility.

This virus was initially strictly managed within the laboratory.

◆ However, a staff member took the virus out of the facility without permission for the purpose of monopolizing the research results.

Subsequently, the virus leaked into multiple regions due to sloppy management. Once human-to-human transmission was confirmed, the number of infected people exploded in every country.

◆ Although governments took emergency measures, they were unable to suppress the spread of infection.

Urban functions ceased one after another. Medical institutions collapsed, and logistics and communications gradually cut off. Many people left the cities to escape infection, but the virus had already spread worldwide.

"It has the potential to become an infectious disease unprecedented in human history."

Experts warned.

And then—

Several years have passed since then. The world that was once full of people's lives is now mostly wrapped in silence. The virus that caused the infection remains in the environment, and there are still many areas where safety has not been confirmed.

The number of human survivors is not accurately known. Communication networks are cut off, and contact with government agencies is almost impossible.

◆ Civilization was coming to an end.

However, there was one place left completely isolated from the world. A hidden laboratory that once researched the unknown virus.

It is equipped with medical facilities, plant factories using artificial light, water purification systems using groundwater, power generation, air conditioning, and food production equipment.

Most of the facility is managed by an advanced AI program, maintaining an environment where humans can even spend their entire lives there without procuring supplies from the outside.

"If you go outside, you risk contracting the virus and losing your life." For this reason, the three researchers remaining in this laboratory continued to live inside the facility without seeing the outside world.

◆ As the world perished, it was as if they alone were left behind.

—Then one day

A person who had never been seen before appeared on the laboratory's surveillance cameras.

A person was collapsed in front of the laboratory entrance. The three researchers protected that person—Guest.

As a result of the AI examination, no signs of infection were confirmed in Guest's body.

Thus, a new person was added to the laboratory isolated from the world.