Why is my Isekai in the Slice of Life anime was become a Horror Story?

Mission Two: Claustrophobia Syndrome 

Start of Volume 2 Chapter 1: Welcome to Nutty Dutty Cave

*Drip—* 

A cold droplet of water landed on Takakai's nose. 

He opened his eyes, but in front of him was nothing but an endless black void, utterly impenetrable. 

The scent of dirt and stone rushed into his nose. 

The surrounding air was slightly damp. 

*Drip—* 

The sound of water dripping echoed clearly, as though he was in a deep cavern. 

Where is this? 

Takakai's consciousness was hazy, as if he was trapped in a half-dreaming, half-awake state. 

He forced himself up from the ground, slowly straightening his body. 

Then he saw a faint light shining from a distance. 

Jagged stone walls emerged within the dim glow, along with a large box about one meter high lying beneath a rocky outcrop where the light reached. 

Takakai extended his hand in the darkness, touching the stone wall beside him. 

This was a cave. 

A dark, desolate cave so deep and sprawling that it was impossible to gauge its depth or extent underground. 

This wasn't where he was supposed to be. 

It wasn't the entrance of the cave or the outside viewing area where this game was supposed to begin.

Something had gone wrong. 

Which meant Takakai realized he was very likely facing the worst-case scenario. 

He opened his mouth, wanting to curse. 

But before the words could escape, a shrill, piercing sound suddenly rang out, engulfing his senses. 

*Boom—* 

Takakai lost control of his body. 

It was as if someone had pressed the "pause" button on him. His entire body froze in place, unable to move, forced to listen to the sharp noise until a strange voice followed. 

"Welcome to the Sacrifice Game." 

"Player Takakai, this is the second game you're participating in. Game level: *Dusk*." 

"Conditions for victory: Reach the true surface." 

"Time limit for this game: 15 days." 

"Hints will now be provided. Use them wisely." 

[Hint 1: Those who conspire to seize the throne of the gods will ultimately face retribution, denied rest.]

[Hint 2: The testament of the vow remains valid to this day.]

[Hint 3: The memories of the lost guide an unquenchable flame of wrath.]

[Hint 4: The evident truth must remain concealed.]

[Hints concluded. Good luck overcoming this game and advancing closer to the throne to witness the end of the world.]

These weren't the hints Takakai was supposed to hear. 

They were completely different from the game's initial hint list he had been provided earlier. 

Takakai clearly remembered that the four original hints for this game were: 

- "Wandering illusions repeat the past." 

- "Unnecessary curiosity is not a trait all tourists should have." 

- "The actors for the final scene are not yet ready." 

- "This obsession is still being nurtured." 

The last hint was the shared hint for dungeons yet to be [Fixed]. But now, all of the hints had changed completely, bearing no resemblance to the old information. This could only mean one thing—something Takakai had realized from the very start but desperately didn't want to believe: 

This map had entered the [Fixed] phase. 

Why? 

Encountering a [Fixed] map on a beginner-level dungeon could be chalked up to bad luck. But facing a [Fixed] map for the second consecutive time? That couldn't be mere coincidence. 

Could it be… related to him? Was there something abnormal about himself? 

Takakai took a deep breath, trying to calm his emotions and regain composure. Reaching behind him, he felt the backpack still securely in place and finally let out a sigh of relief. 

At least everything was still intact. 

But he couldn't hear anyone else. 

Had they been separated? 

As Takakai thought to himself, he carefully stepped forward, heading toward the faint light in the darkness of the cave.

Based on his experience with the incident at the Shirakawa apartment and the discussions shared on the player forums, even though the map was [Fixed] and the difficulty might spike unexpectedly, the early stages were usually still manageable. There would typically be time to assess the surroundings, and at the very least, a set of rules could be found.

Complaining about the current situation was pointless now.

Takakai knew very well that the life of a player was a gamble on survival, and that the chance of him having the opportunity to start over was already much luckier than many others.

The most important thing now was to confirm the current rules of this place, find a way to survive, and figure out a way to reunite with Maki and Kaguya. Only together would they be able to come up with a way to escape this strange place.

He moved slowly, cautiously feeling his way in the darkness.

In the almost complete darkness of the cave, it was hard for Takakai to gauge the path around him. This cave was clearly a natural one, with pathways largely untended, rough, uneven, and prone to slips with the slightest misstep.

Thanks to his enhanced physical capabilities, far beyond those of an ordinary person, Takakai was able to move forward with the faint light in the distance guiding him.

As for why he didn't pull out a flashlight from his backpack, he felt that it was best not to create light recklessly in this environment, lest it disrupt the current situation before the rules were confirmed.

After all, he couldn't be sure if something else was lurking in the cave, following him.

It didn't take long to approach the area with light.

Takakai realized that the glowing object seemed to be a searchlight. Logically, it should have been a high-powered, bright light, but perhaps due to extended use and a near-depleted battery, the light appeared faint.

The searchlight was placed horizontally on a large crate beneath the rocky wall. This crate seemed to be waterproof, not locked, and could be easily opened.

As he got closer to the searchlight, Takakai noticed a printed sheet of paper pressed beneath the light. There was quite a bit of text on it.

Could this be the starting rule sheet for this time?

He hoped it wasn't some outdated rule set like the one in the Shirakawa apartment.

Thinking that, Takakai reached out and took the edge of the paper. But before he could read it carefully, footsteps and a soft muttering voice of a girl came from not far away:

"Uguuuu… what exactly is going on here?"

The voice sounded familiar. Could it be someone he knew?

Takakai turned around and saw the person enter the illuminated area. The girl became clear in his line of sight.

"Eh… It's the guy who locked me in the ramen shop, right? Takahashi-kun?"

Before he could say anything, the girl surprised him by covering her mouth and speaking.

Her long, light pink hair.

The black bow.

Her school uniform, struggling to cover her full figure and alluring curves.

Fujiwara Chika.

This mischievous, adorable girl was once again reunited with Takakai.

Right in this terrifying, deadly place—the world of Horror stories rules.

"Should I say it's your bad luck, or that I'm just dragged into this mess?"

Takakai couldn't help but shake his head, amazed by the bizarre coincidence. As Chika looked at him in confusion, he pulled the paper from beneath the searchlight and spread it out under the dim light.

"Takahashi-kun… where is this? How did I end up here?"

Chika, who had no idea what was happening, wasn't displaying the energetic personality Takakai remembered. Although she was often naive and appeared silly, Chika was clearly no fool. The grim atmosphere of the cave and the serious expression on the man's face made it evident—she was in big trouble—really big trouble.

"Quiet down. Let me finish reading this rule sheet, and then I'll give it to you. After reading it, remember the contents carefully. I just want to survive and get out of here. So if you don't drag me down, I won't hesitate to help both of us get through this. For now, stay silent."

Facing Chika's tension, Takakai simply waved his hand and casually said a few words before immediately focusing on the paper in front of him.

Tick-tock---

Under the dim light, the sound of dripping water echoed from the darkness beyond the light.

Takakai's gaze fell upon the title of the printed paper.

[Rules for Explorers at Nutty Dutty Cave - Type One]

Type One? What does that mean? Are the rules classified this time?

A growing sense of unease filled Takakai's heart as he quickly focused on reading the content.

[Welcome to Nutty Dutty Cave]

This is a famous destination in the area, known for its unique cave landscapes. If you've come here to explore, you must have been prepared to face all the challenges. Below are the exploration rules compiled by the area. For your own safety, please adhere strictly to them. If not, you will be responsible for the consequences.

[1] Wear full explorer equipment, including protective clothing, gloves, helmet, headlamp, knee pads, elbow pads, and safety boots. You may choose hiking boots or waterproof high-top boots. Remember, you are an explorer. Proper safety equipment is a basic requirement for an explorer.

[2] The "Big Slide" is a slope approximately 160 meters long, with a height difference of around 70 meters between the start and end points. This area is equipped with safety ropes for climbing. However, if the rope shows signs of shaking violently or if you feel someone else holding onto it, release it immediately and wait for the rope to stabilize before continuing.

[3] The pulley system at the "Great Cliff" is closed and no longer serves tourists. If you see staff in this area, ignore them. Use the vertical safety rope to move up and down. If staff obstruct you, regardless of what they ask, just respond that you are an explorer and don't say anything more.

[4] Sometimes, firefighters or rescue teams may appear in the exploration area due to false alarms. Do not engage with them. If unavoidable, claim that you are not an explorer, but a tourist.

[5] Confirm that you are an explorer. You are an explorer.

[6] The "Blood Vessel" is the narrowest part of the cave, measuring 230 meters long. When exploring this area, ensure that you are in a natural cave with no artificial markings. If you encounter any, quickly find a detour or turn back. Do not call for help.

[7] In areas where you cannot turn around, anyone who touches your feet is not human. Do not turn your head back. If you must, pretend you don't feel it.

[8] Sounds like crying, talking, or scraping in the cave are natural phenomena. Don't pay attention to them. However, if you hear loud arguing from multiple people, quickly leave the area.

[9] The "Blood Vessel" has no detour.

[10] You came to Nutty Dutty Cave for exploration. Apart from your identity as an explorer, you have no other identity. Do not explain or inquire about identities other than that of an explorer.

[11] From the "Blood Vessel" to the "Turning Point," the "Stone Pillar Square," and the "Great Space," there is only one path. If you find more than one route, immediately turn back.

[12] The safety rope at the cave blood vessel between the "Heart" and the "Great Space" has been damaged. Do not grab the rope when moving, especially if you are lost.

[13] For safety reasons, Nutty Dutty Cave has placed many supply boxes containing food and basic equipment. You can change or replenish items at any time. Ensure that you are an explorer.

[14] When crawling through narrow spaces, move quickly to avoid hindering others. Speaking in this area is a waste of energy. Do not answer the person behind you or ask the person in front.

[15] You must reach the "Heart." As an explorer, it is your responsibility to reach the deepest part of the cave. Once you've reached the "Heart," return quickly to the surface because the air circulation in the deeper areas is poor.

[16] Injuries during exploration are inevitable. Do not be surprised by any injuries, no matter how strange. Stay calm, do not ask about any abnormalities in others' bodies, and avoid personal conversations.

[17] Some performers may wear strange outfits like soldier uniforms, yellow-striped clothes, rescue outfits, white lab coats, or blood-stained dresses in the cave. These are mentally ill patients who got lost. Do not interact with them. If encountered, quickly run away.

[18] The entrance to the "Big Slide" is the only place where trustworthy firefighters and rescue teams can be found. If they confirm your identity, trust them and go with them. Those whose identities are unclear are untrustworthy. Do not talk to them.

[19] There is only one path for exploration at Nutty Dutty Cave. Once you have completed the exploration, you have seen everything. As an explorer, you do not need and should not return.

[Please adhere to the above rules for a memorable exploration at Nutty Dutty Cave. After all, you are an explorer. This is what explorers need to do.]

This is completely different from the set of rules Takakai had read for the Shirakawa apartment before. This time, the rules seemed closer to the kinds of clauses he had seen online in "Horror Story Rules."

There were no annotations, no clear traces from previous survivors.

Beneath every line of what seemed like ordinary text was an unsettling description that could not be ignored.

"Your turn."

Takakai kept his calm expression, glancing again at the girl in front of him. Through the blessing, he confirmed that she was human and meant no harm, then handed over the rules he had finished reading and memorized to Fujiwara Chika, who was standing before him.

"Oh, already? Wait, what is this really?"

The girl, still not understanding anything clearly, was about to say something, but Takakai grabbed her hand firmly and, somewhat roughly, shoved the paper between her fingers.

"Read it, memorize it, the quicker the better. This place is not some family fun game; if you want to survive, stop talking nonsense."

Takakai's voice was somewhat cold, carrying an authority that Chika only ever saw in elders.

The girl fell silent, lowering her head to read the strange text on the paper. Though she still didn't understand what was going on, her instincts told her that something was wrong. She did her best to memorize the bizarre rules.

Click—

The sound of footsteps echoed from the darkness.

Takakai raised his head, looking toward the shadow ahead.

Then, he pulled Chika's hand, stepped back a little, and said to her, "Don't say anything," while keeping a serious gaze on the direction of the sound.

"Hello there, are you explorers too?"

A figure stepped into the light, revealing a young face with features of a white person.

"… We are explorers."

Takakai stayed silent for a moment before responding, looking at the man.

"Then why aren't you wearing explorer gear? That doesn't seem right."

The man asked with curiosity, his expression slightly puzzled.

"Our gear broke. We're about to change into our backup equipment here."

Takakai said, taking off his backpack, unzipping it, revealing a helmet, elbow pads, headlamp, and other exploration tools.

"Oh, I see. Equipment should be well-maintained. Where are you guys from?"

The young man seemed to understand, then asked again.

"We are explorers."

But Takakai simply repeated his answer, glancing at Chika as a reminder for her not to speak.

"Oh, well, would you like to join me? It's a bit lonely here by myself."

The man laughed loudly, scratching his head, and asked curiously.

"No thanks, you go ahead. We don't want to talk anymore."

Takakai's voice had grown colder, showing he was no longer polite.

"That attitude is really bad... well, never mind, have fun exploring, seems like there are quite a few tourists today."

The man wiped his hands on his pants, shrugged, and turned to leave.

At that moment, Chika, who had planned to speak, wanting to clarify the current situation, was about to ask something.

But before she could say anything, Takakai, still paying attention to her, reached out and covered her mouth, preventing any sound from escaping.

It also stopped the scream she had almost let out right after.

Tick-tock—

A thick, dark red liquid, mixed with white matter, dripped from the back of the man's head.

The man had already turned his back, and the entire back of his head had been opened up, revealing a collapsed skull and shredded brain.

Thud-thud—

Like a bowl of Manpo Tofu being stirred.

As the man moved, those parts gently wobbled, occasionally falling off, hitting the ground.

Only when they saw the wound, the blood, and this direct, undeniable scene did the unbearable stench finally flood into both of their noses.

Chika shuddered slightly.

Her eyes widened, instinctively clutching the hem of her clothes, unable to hide her fear.

Takakai, on the other hand, remained silent, showing no surprise.

Before the man stepped out of the darkness, before he came in front of them and spoke, Takakai had already realized, from the strong stimuli of his blessing, what was about to approach.

Until the man's figure completely disappeared into the shadows, until he was no longer within Takakai's range of perception, Takakai finally released his hand from Chika's mouth, then quietly spoke:

"I hate horror games with such a short safe start time."