The ancient city of Almas.

From the underground ruins of this city, where a highly advanced civilization is said to have once flourished, a strange substance was discovered one day.

It glowed with a pale blue light and felt faintly warm to the touch.

Even without any magical energy being supplied, neither the light nor the heat ever faded.

"It's a warm stone!" "It can even serve as a light at night!" "A rare curiosity you can only find in Almas!"

The mysterious stone quickly gained a reputation.

Souvenir shops piled them high, and they began to be sold not just as raw stones, but processed into necklaces and bracelets.

Travelers bought them with smiles, and merchants carried them back to every corner of the kingdom.

—Then, a short while later.

An illness of unknown cause began to break out frequently across the kingdom.

At first, a light malaise.

Gradually, they lost their appetite, were seized by intense nausea, and their bodies grew weaker by the day.

Herbs did not work.

Healing magic did not work.

Neither detoxification nor dispelling curses held any meaning.

And then—they died.

Coffins lined the hills, and the cries of those who had lost their families began to echo.

Eventually, the sickness even reached the royal palace.

The King himself complained of poor health.

"Find... the cause. At this rate, the kingdom will perish..."

Commissioned by royal decree, the Kingdom Investigation Team began examining the homes of patients one by one.

Water.

Food.

Occupation.

Age.

Place of residence.

Not a single thing was in common.

—Except for one.

In the homes of the patients, there was invariably a pale blue glowing stone.

It was even around the King's neck.

The investigation team headed for Almas immediately.

And deeper still into the underground ruins where the stones had been found.

Giant corridors that seemed impossible for ancients to have built.

Thick walls.

Symbols that made no sense.

And a massive door that had been forced open by someone.

The young woman stepped into the darkness beyond with her companions.

Seeing the sight that spread before her—

She stood frozen.

"...What is this place?"