The Phantom Butterfly reached out and grabbed Mo Bai's hand, as if wanting to flee from this frightfully cruel scene.

Mo Bai turned the Phantom Butterfly around so that it would face away from Professor Yang, shielding it from what was happening. She had absolutely no intention of leaving.

Phantom Butterfly: "..."

Was this woman, Mo Bai, simply born without any romantic bone in her body?

Mo Bai did tend to sympathize with the weak, but she knew she couldn't go soft on the Phantom Butterfly. She would never tell it about her plans, and she had to always keep her guard up against it.

Compassion for the weak is a sign of strong empathy, which is a fine quality. But you can't show compassion to just anyone.

After ruthlessly subduing the Phantom Butterfly, Mo Bai held her breath and continued observing Professor Yang.

After torturing No. 107 for half an hour, the assistant researcher standing behind Professor Yang said, "Professor, if this continues, the cancer cells in No. 107's body will be activated. The extract in his system will stimulate the cancer cells' growth, and he will be consumed by them. He'll soon turn into a massive tumor and lose his life."

"Then we'll stop here for today." Professor Yang's tone carried a trace of regret.

The mangled body of Number 107 was dragged out and collapsed onto the floor, barely breathing.

"Does he feel pain?" Professor Yang asked.

The assistant paused, cast Professor Yang a cautious glance, then replied, "We specifically used the extract to enhance his pain receptors. His perception of pain should be ten times that of an ordinary person. At the same time, we modified his brain and body with the enhancement genes from the Enhanced Mutants, so his brain won't be damaged by excessive pain, nor will his body die because of it.

He will remain fully conscious. Consciously alive, consciously enduring the pain, and consciously aware of everything happening to him."

"Excellent." Professor Yang revealed a blissful, faint smile, as though he had just heard something delightful.

No. 107 lay on the ground, glaring at Professor Yang with hatred, and growled hoarsely, "Kill me! Why won't you kill me?!"

Professor Yang looked at him with the eyes of someone looking at trash, and said indifferently, "I didn't die, so why should you? I will live forever and ever, and so will you. I failed to save your son's life; therefore, I will make up for that mistake to you. I will use everything I've learned in my lifetime and exhaust every effort to preserve your life. Wasn't that what you asked for?"

A cruel smile curved his lips.

With a wave of his hand, several grotesque-looking security personnel dragged the cursing No. 107 away.

Watching him, Mo Bai realized that Professor Yang had already lost his humanity.

This didn't mean she sympathized with No. 107. In that old case, Professor Yang had been the victim, and No. 107 deserved punishment.

But now, reshaped by hatred, Professor Yang had lost both his humanity and his empathy.

If he still had empathy, he would only do such things to No. 107. But the current Professor Yang regarded everyone as expendable.

Mo Bai looked toward the test subjects inside the glass rooms, at the monsters constantly slaughtering, devouring, and evolving. They had once been ordinary people. Many had terminal illnesses and only wanted treatment. Yet Professor Yang used them as experimental material.

Mo Bai was certain that Professor Yang was indeed exhibiting symptoms of dissociative identity disorder.

After No. 107 was dragged away, Professor Yang inspected each room one by one. Stopping before a laboratory filled with butterflies, he asked, "Still none with abilities like the Phantom Butterfly?"

The assistant replied, "No. You should know that every individual has both common traits and unique traits. First-stage evolution enhances the common traits, while second-stage evolution enhances the unique traits. The Phantom Butterfly's ability is a second-stage evolutionary trait. Unique traits are, by nature, unique, which is extremely difficult to replicate. Even if we capture countless butterflies, they'll develop new abilities rather than duplicate the same one."

"Even something similar would do," Professor Yang said regretfully. "The Phantom Butterfly can create illusions that cause pain. I really want it to weave a beautiful illusion for that sinner, let him feel happiness, and then personally shatter it to torment him mentally."

The assistant said, "Can't you wait a few more days? The Phantom Butterfly is currently mixed in with those serums. Until we know what abilities the serums possess, capturing it rashly would alert them. Once you become a complete entity and break through the domain's restrictions, could the Phantom Butterfly even escape your grasp?"

Phantom Butterfly: "..."

So Mo Bai was right. Professor Yang really had his eye on it. And reality was even crueler than Mo Bai had analyzed. Because of its ability to inflict pain, Professor Yang had long coveted its power.

If it hadn't clung to Mo Bai this time after returning to the institute, it would have been captured already!

Mo Bai didn't care whether the Phantom Butterfly lived or died. What concerned her the most was the assistant.

She had initially thought that he was just an ordinary researcher. But the way he had spoken just now was too natural, not like a subordinate, but more like someone collaborating with Professor Yang as an equal.

Mo Bai turned her attention to the assistant. He was fairly good-looking in a refined way, with a strong bookish air about him. Tall enough, but his build wasn't muscular at all, nothing like the other monsters at the institute with their bulging muscles.

Professor Yang's attention drifted from the butterfly lab. "I'll go check today's blood test results," he said to the assistant.

The two headed toward a lab with normal walls. Mo Bai quickly pulled the Phantom Butterfly along to follow. Unlike the glass rooms, this lab couldn't be seen into from the outside. They had to go in.

Mo Bai knew it was dangerous, but they still didn't have enough clues about this instance. She needed to gather as much information as she could.

She had used Environmental Rejection on the surveillance element so she could see the Ultra-Star Rank monster in person and find its weakness, but she also needed to understand the true mastermind behind this instance.

That morning, their blood had been drawn right after the extract injection, and now, Professor Yang was going to check the results. An opportunity like this was too rare to pass up.

Pulling the Phantom Butterfly along, she ran lightly without making a sound. The feeling of moving freely like this was wonderful.

She rushed in just before the lab door closed, dragging the Phantom Butterfly inside with her.

Professor Yang and the assistant stood before a screen. They opened a folder and began examining the test reports in detail.

The extract had enhanced Mo Bai's constitution, and her eyesight was improved along with it. Even though the words on the screen were small, she could still read them perfectly.

The reports he was reviewing belonged to the seven players: No. 007, No. 018, No. 025, No. 251, and several others.

"Truly worthy of being called monster slayers," Professor Yang said with satisfaction. "The special energy in their blood is strong. Even after the injection, their genes haven't changed at all. Once they use the serum, I can finally be complete."

His words aligned perfectly with Mo Bai's analysis. He was waiting for the players to use the serum, taking advantage of the system-provided serum and the players' unique energy, referred to by the system as positive flow, to suppress the power of the Ultra-Star Rank monster. This way, he could merge with the monster and gain control.

"When the time comes, don't forget our contract," the assistant said.

"Even if I wanted to break it, I couldn't," Professor Yang replied.

"How long until they use the serum?" the assistant asked.

Professor Yang glanced at the reports again. "Right now, their special energy can fully suppress the extract's power. After the second injection, the two energies will be equal. They'll still be able to resist mutation at that point, so they probably won't use the serum. Only after the third stage, when the extract's power completely overwhelms them, will they need it.

"That said, being able to resist doesn't mean they won't use it. Some coward might inject early, and that won't do. The five serum injections have to happen within a 24-hour window."

"Then we'll need to find a way to make them all use it during the third phase," the assistant said. "Du Ying devoured the brain essence of two serums today, didn't it? Did it retrieve any memories? Does it know where the serum is hidden?"

"No," Professor Yang sighed. "That part of the memory is sealed by a powerful force of rules. Du Ying's power can't break through it. Only my half-body underground can break through that seal, but you know how difficult it is to communicate with. Even I can barely reach it. If it were possible to communicate, we would have merged long ago."

"Then we'll think of something else. It's only the first day. There's still time," the assistant said.

The two opened the lab door and walked out, still talking. The moment the voice-controlled door opened, she pulled the Phantom Butterfly through and ducked into a corner by the wall.

After they left the experimental zone, Professor Yang seemed unbothered. The assistant, however, glanced toward the direction where Mo Bai and the Phantom Butterfly were hiding.

"What are you looking at?" Professor Yang followed the assistant's gaze but saw nothing. Just an empty corner.

"I don't know," the assistant said. "Something feels off, just call it intuition. Ask the surveillance robots where those serums are."

Professor Yang raised his wrist and sent a message through his watch.

"The two Schizophrenics are in their rooms. The two whose brain essence was absorbed are also staying put. The woman in No. 018 is wandering the public area, chatting with people. The remaining man and woman are in Room 007 with the Phantom Butterfly. And the stupid researcher without serum is in the archives."

"Two lunatics and two idiots. That's already four out of the fight," the assistant said. "As for the remaining three... let's stir up some discord between them. No. 018 likes chatting, right? Send someone clever to approach her. Have them claim to be a survivor from the previous batch of investigators who can help her escape, but can only take one person. That should make her wary of the other two."

"Why not No. 007?" Professor Yang asked.

No. 007 was Mo Bai.

The assistant looked puzzled. "Why would we pick No. 007? She's sharp and hard to deceive. She won't easily trust strangers."

"I'm not sure." Professor Yang shook his head, hands clasped behind his back. "I just have this urge to feed her to the thing underground as soon as possible."

The two continued chatting as they left the experimental zone. Mo Bai did not follow.

She had gathered enough information here. And the assistant's earlier glance toward their hiding spot proved that his instincts were sharp. He had sensed their presence. The only reason he didn't investigate further was that Professor Yang's surveillance robots had confirmed the players' exact positions.

Following them any further would be dangerous.

She glanced at the trembling Phantom Butterfly and signaled for it to keep moving.

The Phantom Butterfly made a pitiful expression, clearly not wanting to go any further.

But there was no way Mo Bai would give up such a useful mimicry ability. She grabbed its hand and headed for the fourth basement level.

To be honest, if she hadn't known that Professor Yang already had his eye on the Phantom Butterfly, she would have turned it into a card long ago.

Keeping an A-rank monster by her side was simply too dangerous. It gave her the constant unease of bargaining with a tiger for its skin. Turning it into a card would have been far more reassuring.

The Phantom Butterfly seemed to sense Mo Bai's killing intent. When they reached a deserted spot, it looked up at her with watery eyes and typed on its watch: "Mo Bai, I love you. Do you love me? But you're a player. Would you ever fall in love with a monster?"

Looking at its expression, Mo Bai had the feeling that if she didn't answer carefully, it might turn and run away. After that, she would lose her chance to get close to the Ultra-Star Rank monster underground.

So she thought it over for a moment and wrote down an honest answer: "I like your appearance now, so I enjoy looking at your face. But you haven't stirred my heart. I like an obedient, loyal, and docile person who would overcome their fear for my sake. As for whether you're a player or a monster, that doesn't matter to me."

The Phantom Butterfly typed another line: "All right, I'll overcome my fear and go with you. But you have to promise that you'll try your best to fall in love with me. Okay?"

Mo Bai replied sincerely: "I'll try."

But trying doesn't necessarily guarantee results.

Only after receiving her promise did the Phantom Butterfly follow her down to the fourth basement level.

Just as Mo Bai had expected, there were no guards on the fourth floor.

The so-called five guardians of the Ultra-Star Rank monster weren't guarding the massive being underground at all. They were guarding the powerless Professor Yang.

From the staircase between the third and fourth floors onward, there was no one. Not a human nor a monster.

To prevent the Phantom Butterfly from launching a sudden attack, Mo Bai held its hand with the one that wore the Spatial Blade glove, walking side by side as they descended.

The moment she stepped onto the fourth floor, she felt an overwhelming, terrifying pressure.

Basement Level Four only had a row of dim ceiling lights. A corridor ran along the walls, and the rest of the space was completely empty. Looking down from the corridor, there was nothing but a bottomless abyss.

She had barely stepped onto the walkway when a soft black tentacle shot upward and pressed itself against the glass wall outside the corridor.

Mo Bai saw an eye growing from the tentacle. It swept back and forth across the spot where she and the Phantom Butterfly stood.

After searching for a while and finding nothing, the tentacle slid down, seemingly disappointed.

A moment later, Mo Bai gathered her courage and leaned over the edge to peer down. Below, she saw a massive, pitch-black mass that was constantly writhing and shifting.

Compared to that monster, she felt as insignificant as an ant.

Mo Bai took a card from her inventory. It was the B-rank card Prying Lenses that had played a crucial role in the previous instance.

The Prying Lenses weren't especially rare in theory. It dropped in a B-rank daily instance, but the drop rate was absurdly low, roughly one in a thousand runs, so it was almost never seen on the market.

However, Sheng Yan happened to be an instance-grinding fanatic. He also owned Prying Lenses, and before entering this instance, Mo Bai had selected that card for him.

Information Extraction, Recorder, and Prying Lenses. Those three cards were everything Sheng Yan had brought for this instance.

Mo Bai had chosen this card because she was deeply familiar with it, and because Prying Lenses functioned very differently in her hands than in anyone else's.

She put on the glasses and temporarily boosted its rank, then directed her gaze toward the Ultra-Star Rank monster hidden deep underground.

She needed to see for herself whether it was truly as difficult to kill as Du Heng had claimed.

Du Heng's Weak Point Detection ability had been suppressed to the beginner level by the instance rules. Even if he could see the monster, he might not be able to perceive its true weakness.

But an upgraded Prying Lenses might reveal more.

To push Prying Lenses to its absolute limit, Mo Bai chose not to use the Recorder, which had previously stored her abilities. Instead, she consumed the Intermediate Nutrient Potion worth twenty thousand points to fully restore her energy. She intended to channel everything she had into the card.

She poured most of her energy into Prying Lenses and successfully raised its rank match her current intermediate level ability.

This time, Prying Lenses was even stronger than in the previous instance.

In an instant, it could capture images hundreds of meters away. It could even penetrate biological bodies, letting her see their internal structures.

But the energy contained within the Ultra-Star Rank monster was overwhelmingly powerful. Mo Bai only managed a single glance before a splitting pain erupted in her head, so intense that she nearly vomited.

She immediately pulled off the glasses. Even then, she stayed alert to the Phantom Butterfly beside her, making sure not to let it see how badly she was suffering.

The Phantom Butterfly lifted its watch in front of her. The screen read: "Well? Did you see it?"

In Mo Bai's vision, the words overlapped in four layers. Like someone with severe astigmatism, she struggled to focus long enough to read them.

But she showed nothing. She smiled calmly, raised her wrist, and slowly typed on her watch.

Painstakingly but accurately, she typed out three short words: "We'll talk after we return."

The Phantom Butterfly couldn't wait to leave and rushed ahead to quickly exit the fourth floor.

Mo Bai felt a mouthful of blood rise to her throat, and the metallic taste of rust spread through her mouth. She forcefully swallowed it and followed the Phantom Butterfly out as if nothing was wrong. She walked steadily through the experimental zone and all the way back to the second floor.

After arriving in front of room 007, Mo Bai knocked on the door.

Sheng Yan opened the door, stepped out, and looked around for a moment. Taking advantage of the gap, Mo Bai and the Phantom Butterfly slipped inside.

Back in the room, Mo Bai sat directly in the wheelchair, and propped her forehead against her palm as if deep in thought.

The Phantom Butterfly dropped its mimicry.

When Sheng Yan saw Mo Bai, he immediately moved closer and said to the Phantom Butterfly, "At least you know what's good for you."

"I've been very well-behaved," the Phantom Butterfly said, gazing at Mo Bai. "Mo Bai, my sense of smell is very sharp. I know you're hurt, but I never harmed you the entire way back. I truly want you to like me, so I want to become the kind of person you'd like. I'm even restraining my instincts for you."

It crouched by her feet like a puppy.

"You're back in your room now, back with your companions. You don't need to keep pretending anymore."

Since the Phantom Butterfly had already seen through her, Mo Bai stopped forcing herself. She pulled out a tissue and spat the blood she'd been holding back into it.

Seeing her spit blood, Sheng Yan grabbed her hand, alarmed. "What happened? Who hurt you?"

Mo Bai shook her head. "I'm fine. I just... looked at the Ultra-Star Rank monster."

"Just looking at it did this to you?" Sheng Yan exclaimed.

If the monster was so powerful that a single glance could cause this kind of injury, how were they supposed to fight it?

"It's not that extreme," Mo Bai said. "I got hurt because I used Prying Lenses to see the monster's true nature. Through the card's power, my optic nerves connected to the monster's nervous system. In that instant, my body bore the full brunt of its power, and I suffered backlash."

"What did you see?" the Phantom Butterfly asked.

Mo Bai looked at it with distrust plain in her eyes.

She certainly saw the hope for victory.

But she still didn't trust the Phantom Butterfly, so she couldn't reveal her discovery in front of it.

Disappointment flickered across the Phantom Butterfly's face, but it was obedient enough not to press further. Instead, it stepped back, opened the door, and said, "I'll leave now. Once I'm gone, you can talk."

As it stepped out, it didn't forget to remind her: "Do you remember our earlier agreement? Will you truly try your best to keep it?"

Mo Bai's lips moved, but she didn't say the word yes.

She was worried that spoken words might carry binding force and that the Phantom Butterfly might possess that kind of ability. She was worried that saying it aloud would become a trap.

The Phantom Butterfly gave a bleak smile. "It's fine if you don't keep it."

With that, it closed the door and left.

After it was gone, Mo Bai placed her hand over her heart and let out a quiet sigh.

"Phantom Butterfly... you're truly formidable."

Even knowing full well that it was a soul-devouring monster, she still found herself feeling some kind of uncontrollable guilt.

She understood herself well. Her strong-willed personality and tendency to dislike owing anyone made it easy for guilt to turn into affection.

"Don't worry about it. It's just a monster," Sheng Yan comforted. "What about your injury? Do you need some healing potion?"

"No need. I'll be fine after some rest," Mo Bai replied. "Help me call Liu Congyi and Du Heng. I saw something extremely important. We need to hurry and act as soon as possible."