Before they knew it, it was already eight o'clock in the evening. Mo Bai and the other players began experiencing an intense, almost unbearable thirst.

As a researcher, Du Heng immediately carried out his duties. He hurried back to his office, retrieved a beverage meant to relieve the symptoms, and delivered one to each of them.

After Du Heng's explanation, everyone learned that this symptom was actually a rejection reaction of the body's immune system to the extract.

At the beginning, the extract drastically alters the human body to accelerate its evolution. That's why the initial reaction is so intense, and severe pain is completely normal. Once the body adapts to these changes, the extract's flow can no longer be felt. However, the immune system is still working. It can sense that this foreign substance is harmful.

Thus, at a specific time every day, the test subjects would feel thirsty. It was the immune system's way of urging them to drink large amounts of water, hoping to flush the extract out of their bodies.

At that point, the research institute provides this special beverage. Besides quenching thirst, it also helps the extract numb the immune system and achieve immune evasion.

If the subjects fail to drink it regularly, their bodies will suffer more and more. Once the immune system realizes it cannot expel the extract, it will attack the body that has been modified by it, treating the body itself as harmful.

In short, from the immune system's perspective, it's either reject the extract or reject the evolved organs. Simply, let the extract die, or everyone dies together. The whole approach boils down to indiscriminate destruction.

Du Heng told them that once Phase One ended, the immune system would fully adapt to the extract and would no longer produce a rejection reaction. That would make the Phase Two injections far less painful, but it wasn't good news either. It meant that their bodies had become completely defenseless, allowing the extract to alter them at will.

If they could eliminate the Ultra-Star Rank monster before Phase One concluded and avoid the second round of injections, then their bodies would remain normal. Even if they returned to the Infinite World, all of them would be fine.

Their injuries would be healed, and they would gain the benefits of the instance without being excessively altered by the Ultra-Star monster. And with the monster dead, they would no longer be under its control.

As long as their plan succeeded, everyone would have a bright future.

After drinking the special beverage and reporting their physical conditions to Du Heng, everyone went about their respective tasks.

Liu Congyi continued as usual, casually chatting with others and drawing energy from social interaction. The institute's mandatory lights-out was at 10 p.m., leaving her over an hour to talk.

Du Heng returned to his lab, searching within his permitted range for the investigator whom they hadn't met yet.

This time, Du Heng was extremely cautious. He knew he no longer held any value, so the institute would no longer indulge him as it had before. If he enters a restricted area again, the consequences would be severe.

Mo Bai told Sheng Yan to rest in her room while she took the Phantom Butterfly to conduct an experiment.

She wanted to test her new ability, Environmental Rejection, and see what it could truly do.

Mo Bai tried using it to expel the extract inside her body, but failed.

Xiao Qi explained that she rejects the environment, not individual lifeforms. If a harmful element is shared among all lifeforms, then it is treated as part of the environment and can be rejected. But harmful elements inside a single individual do not count as an environment, so it cannot be rejected.

Through Xiao Qi and the system's explanations, Mo Bai gradually understood the purpose of her new ability.

Therefore, the first thing she planned to do that night was to court death.

She was going to the institute's restricted area with the Phantom Butterfly to personally see the Ultra-Star Rank monster hidden deep underground.

Her ability required her to understand over 50% of the environment. However, she hadn't fully grasped the environment of the institute since there were too many restricted areas, and this limited her ability's effectiveness.

She had no choice but to go.

It was a necessary risk, and also an experiment for her own power.

She believed that the surveillance was part of the environment, and it was a highly harmful element that interfered with her assimilation. With that in mind, she should be able to reject the element of surveillance.

If she could remove surveillance, they would be able to move freely in the institute, make preparations in advance, and accomplish far more tasks.

But if they couldn't escape surveillance, they would be constrained at every turn, and none of their plans would succeed.

This was an experiment that had to be done. Even if failure meant death, it was worth the attempt.

And precisely because death was a possibility that Mo Bai only brought the Phantom Butterfly along.

The Phantom Butterfly's mimicry ability could deceive the guards' vision. If the experiment failed, it could still escape through the central air-conditioning system.

As always, it was a plan where no one but Mo Bai might die. A very Mo Bai way of doing things.

She was currently on the first basement floor. The institute had unusually high ceilings: B1 was five meters high, B2 ten meters, B3 eight meters, and B4, where the Ultra-Star Rank monster resided, had a ceiling height exceeding one hundred meters.

The effective radius of Environmental Rejection was 100 meters and the distance from her room to B4 was just within that range.

Mo Bai and Phantom Butterfly would begin using Environmental Rejection inside her room to remove surveillance elements. Afterwards, the Phantom Butterfly would use environmental mimicry to conceal them from the omnipresent cameras.

With her room as the center point, as long as Mo Bai didn't descend deeper than 100 meters underground, the institute wouldn't detect her.

Standing in her room, she activated Environmental Rejection.

In that instant, the entire institute vanished from her sight. All she could see were colors representing different symbolic meanings.

She herself was white. Elements in her surroundings that were beneficial or harmless appeared white or near-white, while harmful elements were gray or even black.

With her current ability, she could only reject the gray elements, and the black ones were beyond her power.

She simply wasn't strong enough yet.

Perhaps once she reached Intermediate-9, she would be able to completely eliminate the black elements.

Mo Bai reached out to touch a black patch, trying to sense its nature.

The moment she made contact, she felt an overwhelming malice.

It was the institute monsters' deep hostility toward the players.

There was malice from Du Ying, Phantom Butterfly, and other monsters that she had never seen.

She couldn't withstand such terrifying hatred, which nearly swallowed her soul. She immediately pulled her hand back.

Drenched in sweat, Mo Bai had to rest for a while before recovering.

Just as she had suspected, the institute's monsters were aware of the players' existence and harbored deep hostility toward them, even the Phantom Butterfly, whom she had already subdued.

The Phantom Butterfly was essentially manipulated into submission, obeying her only to survive. It might have a trace of goodwill toward Mo Bai herself, but that didn't mean it liked players.

The entire institute was saturated with black elements. After that experience, she didn't dare touch them again.

At the same time, she noticed a tiny black dot in her item inventory.

She didn't touch it and only memorized its location. After deactivating her ability, she planned to check what that black dot was.

Then, she turned to the gray elements.

These were negative but not terrifying things: the test subjects' pessimistic emotions, the researchers' indifference toward them, the institute's security doors, and various other oddities.

After feeling through all the gray portions, she located the surveillance elements targeting the subjects and researchers.

She couldn't eliminate the surveillance over the entire institute, since that would draw too much attention and put the institute on high alert. Instead, she selectively removed the surveillance elements targeting herself and the Phantom Butterfly.

After finishing, she withdrew from her ability state and realized that she had collapsed onto her bed, utterly drained, both physically and mentally.

Sheng Yan stood guard beside her, holding the Recorder card to prevent the Phantom Butterfly from attacking while she was weak.

That was also why Mo Bai had asked Sheng Yan to stay in her room. She didn't trust the Phantom Butterfly.

"Do you really have to go tonight? You're in bad shape," Sheng Yan said.

"I have to," Mo Bai replied. "I'm just a little unaccustomed to using my intermediate-level ability, that's all. It's nothing serious. I've realized the rejection has a time limit. I didn't completely eliminate the element, but only expelled it temporarily. By tomorrow, the surveillance will likely be restored."

She wiped away her sweat and ate a little. Once her complexion improved, her calm, composed expression returned.

She would be acting together with Phantom Butterfly this time. If she appeared weak, she wouldn't be able to suppress it.

Her energy was depleted, but she didn't plan to use her only Intermediate Nutrient Potion just yet. She only had one bottle, so she had to save it for when it truly mattered.

Tonight was only reconnaissance. There would be no combat, and she only needed to guard against the Phantom Butterfly.

And the Phantom Butterfly was the kind of creature that grew meek when she was strong and bold when she was weak. As long as she projected strength, it wouldn't dare act rashly.

After resting a while and putting on a confident front as though she'd fully recovered, Mo Bai prepared to leave with the Phantom Butterfly.

Before going out, she retrieved the small black dot from her inventory.

She wanted to know what item she possessed that was completely harmful to her.

When she took it out, she was stunned.

The black dot was the scene card she had obtained in the previous instance: Ruins of the Count's Castle.

It had been a reward from the system, and she even thought that she could use it to establish her own domain in the future. She never imagined that this card was harmful to the point that it was something her Environmental Rejection would eliminate.

That meant that even if she reached the advanced level and awakened Environmental Assimilation, she still wouldn't be able to use this card.

The system's description had also advised against using it.

With more urgent matters at hand, Mo Bai could only put the harmful card away in confusion.

She put on her Spatial Blade gloves and borrowed the Recorder card from Sheng Yan.

With this card, she could optimize and upgrade the Spatial Blade into something far more powerful at any moment.

That way, even if the Phantom Butterfly betrayed her midway, she could still subdue it with the help of both cards.

The Phantom Butterfly obediently activated its mimicry ability, rendering both itself and Mo Bai invisible. Others couldn't see them, but as long as they stayed within two meters of each other, they could still see one another.

Moreover, the Phantom Butterfly's ability couldn't mask sound, so they couldn't speak.

Sheng Yan opened the door and strolled outside for a while, looking as though he were taking a casual after-dinner walk. In reality, he was opening the door for Mo Bai and Phantom Butterfly. If the door had opened automatically and no one walked out, it would certainly have aroused suspicion.

Silent, Mo Bai and the Phantom Butterfly headed toward Basement Level Four, passing unimpeded all the way up to the warning sign marking the restricted area on Basement Level Three.

Even though she had already expelled the surveillance element, Mo Bai was still nervous. If her ability failed, the Phantom Butterfly might have a chance to survive, but she would undoubtedly die.

She gestured for the Phantom Butterfly to remain outside the warning line and entered the restricted area alone.

Based on Mao Juncai and Zhuang Xiangyang's previous experience, if she were discovered, an A-rank monster would arrive to deal with her within ten minutes.

Mo Bai stood inside the restricted zone for roughly half an hour, but no one came.

Watching her, the Phantom Butterfly felt a surge of intense, complicated emotions.

It feared Mo Bai. She was a player who grew at an astonishing speed, possessed an unyielding mind, and controlled formidable abilities. In schemes, intelligence, and power, the Phantom Butterfly was no match for her. This was the instinctive awe of the weak toward the strong.

It liked Mo Bai. She had a beautiful appearance, a resilient soul, and the kind of tender affection Phantom Butterfly adored. It also liked staying by her side and liked the taste of her soul.

But at the same time, it hated Mo Bai because it was dominated in every way. The Phantom Butterfly had once escaped from the institute; that alone proved it longed for freedom. It did not wish to be bound by anyone or anything.

These tangled, contradictory emotions churned within its soul and led it to a single conclusion: it must kill Mo Bai.

If possible, it would devour her soul, which would truly be the most exquisite soul it had ever tasted. It would forever remember that trembling flavor of intertwined love and hatred.

If it couldn't find the chance to devour her soul, then at a critical moment in battle, it would use the institute's power to kill her.

It would remember the expression on her face at the moment of her death and spend its life mourning this beautiful woman.

To achieve that goal, it would become whatever Mo Bai liked: foolish, obedient, sensible, compliant, and beautiful. It would imitate Sheng Yan, imitate the mutants around her, and circle her like a large puppy. Until the day she died, it would be her most loyal dog.

After all, it was Phantom Butterfly, the creature that understood human preferences the best. It could transform into whatever form humans favored, and even Mo Bai would be no exception.

When Mo Bai waved at it, signaling that the restricted area was safe and it could enter freely, the Phantom Butterfly revealed a gentle, docile smile and trotted toward her, eyes full of admiration for the strong.

They passed through the third floor. There, Mo Bai saw even more monsters.

These monsters did not appear in the test subjects' activity zones; instead, they stood guard outside the laboratories.

The Phantom Butterfly stared blankly at one laboratory door and stopped moving.

Mo Bai couldn't be more than two meters away from it, or the mimicry would fail. Seeing its expression, she looked at it in confusion.

The Phantom Butterfly lifted its watch and typed a few words for her to see: "I was born here."

After she read the message, it silently deleted the text.

This was their agreed method of communication: typing without sending, then deleting. As long as the message wasn't transmitted, the institute couldn't monitor the watch's signal.

Mo Bai couldn't help but look toward the laboratory it was watching.

It wasn't particularly secretive. The walls were made of glass, allowing her to clearly see the experiments taking place inside.

In one glass chamber, a group of monsters injected with the extract was devouring one another. The scene was horrifying.

In another chamber, mutants and various beast- and insect-type monsters were also consuming each other.

Mo Bai began to understand how monsters like Du Ying had come into being.

It was gu breeding.¹

Evolved monsters were placed together to devour each other. Since their bodies had already been modified by the Ultra-Star Rank monster's extract and completed the immune adaptation, they wouldn't reject other monsters' flesh. Instead, they easily fused and became ever more powerful.

The Phantom Butterfly had been born in this kind of environment.

It pointed to another room. Following its gesture, Mo Bai saw a massive lump of flesh that was constantly dividing and proliferating.

Researchers in gray uniforms continuously threw living monsters into the glass chamber. The creatures struggled desperately but were still swallowed by the grotesque mass.

After thinking for a moment, Mo Bai typed on her watch: "Could this be the tumors from those cancer patients?"

All the cancer patients among their batch of test subjects had already died, each transforming into this kind of massive flesh tumor before death. The institute had destroyed the tumors, but they had cut a sample for research.

If those proliferating tumor tissues were placed together and allowed to consume one another, a new giant mass would quickly form.

Phantom Butterfly replied: "Probably."

Mo Bai typed: "Is the institute constantly feeding monsters and mutants to it in order to cultivate something that can subdue it?"

Phantom Butterfly answered: "Yes. If something truly absorbs this mass, they would become what you players call an S-rank monster."

Mo Bai's heart skipped a beat.

The Ultra-Star Rank monster alone was terrifying enough. And yet the institute was still manufacturing other strong monsters.

She typed: "What if no one can conquer it? What if it keeps growing? And even if someone absorbs it and becomes S-rank, what if they refuse to obey?"

The Phantom Butterfly didn't reply. Instead, it pointed downward.

Mo Bai understood.

Of course. The institute didn't need to worry about controlling the tumor or rebellion.

Deep underground lurked the most powerful Ultra-Star Rank monster. Anything uncontrollable and disobedient could simply be fed to it.

Mo Bai also realized what Professor Yang intended.

He wanted to become stronger.

The agony of being unable to protect his family or himself made him desperately crave strength. He already become an Ultra-Star Rank monster beyond ordinary domains, yet he was still building a powerful, loyal army of monsters.

As she was contemplating his motives, a neatly dressed, refined-looking middle-aged man approached, radiating an air of intelligence and composure.

He stood before the glass wall containing the massive tumor, quietly watching as a mutant was devoured.

Yes, watching with appreciation.

From the depths of his calm eyes, Mo Bai detected a flicker of madness.

The Phantom Butterfly pulled her aside and rapidly typed on its watch, holding it up for her to see.

She didn't even need to read it. She already knew. The Phantom Butterfly was telling her that this man was Professor Yang, the leader of the entire Biological Research Institute No. 7.

After watching the mutant being completely consumed, Professor Yang smiled in satisfaction and asked the researcher beside him, "How is his physical condition? Can he endure this level of erosion?"

The researcher opened a tablet and pulled up a biometric analysis. "The extract concentration in his body exceeds seventy percent. Even while being continuously devoured, his body can regenerate repeatedly. He won't die anytime soon."

"Then bring him here," Professor Yang said gently, almost courteously.

Mo Bai held her breath and remained hidden with the Phantom Butterfly in a corner, observing his every move.

After a while, two researchers escorted someone over.

Mo Bai recognized him immediately.

It was No. 107, the man whose body was saturated with extract and had been screaming at the mechanical arm.

Seeing Professor Yang, No. 107 shouted hysterically, "Kill me! You've already killed my family! How can you still let me live? Kill me!"

Professor Yang didn't speak. He merely lifted his hand slightly, and the researchers shoved No. 107 into the glass chamber containing the massive tumor.

Afterward, someone beside Professor Yang handed him a tissue.

Professor Yang slowly wiped his hands.

His hands didn't touch anything. He only gestured toward No. 107 from a distance, yet he wiped them carefully, as though he had come into contact with something filthy.

Watching No. 107 struggle in agony, Mo Bai suddenly realized who he was.

It was him. The family member who had thrown sulfuric acid at Professor Yang, burned down his house and caused his wife's death.

At that moment, Mo Bai understood what the man had been shouting repeatedly at the mechanical arm during the injection.

He was screaming... "Kill me!"