Year 1938.

After the full-scale invasion of China by the Japanese army, Japan stationed "Epidemic Prevention and Water Supply" troops, essentially bacteriological warfare units, throughout various regions to develop and produce bacterial weapons.

When a large unit of the bacteriological troops was stationed in the city of Liguo, they forcefully occupied some civilian residences near the school.

They constructed the most important laboratories underground to evade scrutiny and to prevent potential leaks.

These malevolent individuals captured many civilians for large-scale human experiments.

Men, women, young and old were all subjected to these experiments.

Many civilians were live dissected and their organs were harvested, ultimately tortured to death, with their agonizing cries echoing underground for a long time.

The bodies of the deceased were thrown into cremation furnaces, their chimneys protruding from the ground, billowing smoke day and night.

Nowadays, people still find rooms filled with human bones in what used to be the cremation areas.

However, after this situation persisted for several years, something unusual occurred.

A soldier suddenly went mad and bit a military officer to death.

In his madness, he exhibited immense strength, requiring several soldiers to subdue him only after much effort.

However, this soldier never regained his sanity, speaking incoherent words, at times even in Japanese.

To avoid further complications, they immediately threw him into the cremation furnace to be burned alive.

Unexpectedly, the next day, another soldier went mad with the same symptoms as the previous one.

Believing that the madness was caused by the leakage of some microorganism affecting the brain, the unit thoroughly disinfected the underground area.

Yet when they were incinerating the second soldier's body, two workers involved in the cremation also went mad, shouting in Chinese, "Take my life!"

Only then did they realize that they might be dealing with ghosts.

With the war effort steadily deteriorating for Japan, they were unwilling to abandon the laboratory, so they brought in several Japanese onmyoji (yin-yang masters) to try to exorcise the spirits.

However, the onmyoji were possessed by ghosts as soon as they entered the cremation area, and no amount of rescue efforts could save them.

Desperate, the Japanese sought help from various local shamans and witch doctors.

Eventually, a local cult called "Interflow Sect" collaborated as traitors to help the Japanese solve this issue.

After a detailed investigation, the cult leader discovered that the cremation area was situated right over a concentrated pool of negative energy, a so-called "Pool of Yin Gathering".

The numerous deaths and wandering souls in that area prevented reincarnation, causing the resentment to grow stronger and the hauntings to become inevitable.

To show their loyalty to the Japanese, the cult leader also taught the onmyoji some spells and formations.

In 1945, Japan was defeated and surrendered, and orders were given to destroy all evidence and retreat immediately.

But an unexpected incident occurred.

A fanatic onmyoji, adhering to imperialistic beliefs, attempted to activate a formation to sacrifice all the people in the city for the sake of "glorious death".

The method involved laying down a "Ten Tribulations Formation" in the cremation area to control the flow of negative energy.

Once activated, no one in the city would survive.

To stop this evil onmyoji, the cult leader intervened.

He had a change of heart out of conscience and the fear of perishing along with the others. Moreover, the leader had his own ulterior motives.

Upon being brought to the site by the onmyoji, he realized that by using a "Life Altering Formation" at the "Pool of Yin Gathering", he could reverse the flow of negative energy to achieve an almost immortal effect for himself.

Feigning allegiance to the Japanese, he taught the onmyoji how to set up the "Ten Tribulations Formation", intending to use it as a means to execute the "Life Altering Formation".

With the downfall of Japanese forces imminent, the leader attempted to activate the formation for his immortality. Yet he didn't expect the stubborn onmyoji to act on his intent for "glorious death".

A fight ensued between the two, and the unscrupulous onmyoji used a gun, resulting in mutual destruction.

The onmyoji, with his last breath, tried to activate the formation but failed due to his injuries, causing a leakage of the negative energy from the "Pool of Yin Gathering", leading to his eventual death.

Principal Dai recounted with a chilling response, "When I came to the underground laboratory looking for my mentor, the cult leader, I found him dead alongside the onmyoji. We searched their bodies and found seven soul bottles containing the formation diagram."

Those seven bottles were the ones we unearthed with Fuko, filled with the ashes and souls of those who perished at the hands of the Japanese.

If placed in the formation of the Big Dipper at the spot of the "Ten Tribulations Formation", which was the cremation area, it would rekindle the negative energy in the "Pool of Yin Gathering".

Once the negative energy filled up, the souls in the bottles would break free, creating a haunting, notifying the formation setter.

When Principal Dai was only in his teens, he pretended to be an orphan and gained the trust of an elderly couple, living as their adopted son.

After Japan's defeat, with the internal turmoil within China, the retreating Japanese destroyed many details of the underground laboratory during their withdrawal.

The national government did not conduct a thorough investigation, and after sealing the underground laboratory, demolished the chimney of the cremation furnace and placed a nameless stele to suppress the souls.

After the school resumed operations, and following the Kuomintang's defeat, the underground secrets remained undiscovered.

Many years later, Principal Dai meticulously returned to work at the school, secretly burying the soul bottles, waiting for the right moment to activate the formation.

During the construction of air-raid shelters in the sixties, he feigned surveying the terrain and drafted an excavation plan, avoiding the original underground laboratory site, secretly modifying it to its current state.

"After waiting all these decades, the negative energy of the 'Pool of Yin Gathering' has finally re-concentrated to a usable state. I intended to use it secretly for my immortality but found one of the bottles' souls to be inside you. With your investigation into the old school archives, I decided to give you the map, leading you here."

Who would have thought there were so many horrifying events and twists?

"Old man, after all this ranting, you still haven't said what you brought me here for."

"The formation requires the fresh blood of seven human souls at the formation's eyes to activate it. I struggled to find living people until you sent yourself to my door. That vengeful soul inside you, I don't know where it has gone, so I'll just use you instead."

With that, Principal Dai suddenly moved with ghostly quickness, raising his cane to strike my head.

All this time, while talking to him, I was signaling Fuko to disperse, planning to tackle this old man after separating him.

But I didn't expect an elderly man over eighty years old to be so agile, likely due to his use of some rejuvenation spells.

I completely overestimated my reaction speed, closing my eyes and using my hands to block the cane, yet not feeling any impact after a while.

Opening my eyes, I saw Principal Dai with stiffened hands mid-air, eyes rolling back, his face turning pale with sweat flowing down, producing hoarse sounds from his throat.

What's wrong with this old guy? I turned to look at Fuko, who seemed equally puzzled.

Suddenly, Principal Dai fell face down with a thud, revealing a piece of yellow talisman paper with strange patterns stuck to his back!

Behind him, a figure slowly approached, holding a stick; it was Granny Hua!