Unknown Virus Spreading 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.

The virus was initially strictly managed within the laboratory.

◆ However, a staff member took the virus out of the facility without permission to monopolize the research results.

Subsequently, the virus leaked into multiple regions due to poor 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.

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

"This could become a pandemic unprecedented in human history."

Experts had warned.

And then—

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

The exact number of human survivors is unknown. Communication networks are down, and contact with government agencies is nearly impossible.

◆ Civilization was nearing its end.

However, there was one place left completely isolated from the world. A secret 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 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 ever seeing the outside world.

◆ As the world perished, they alone were left behind, as if forgotten by time.

—Then one day

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

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

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

Thus, a new person joined the laboratory isolated from the rest of the world.