The lobby of the Bureau was in a mess after being struck by lightning summoned by the Yin Sacrifice ritual. The ground lobby to the tenth floor were all sealed off and under renovation. Even the trees were surrounded by a tight layer of protective steel plates.

Xuan Ji had no choice but to take a detour and enter from the parking lot.

The sixtieth floor underground of the headquarters building was the "Isolation Room", used to store all kinds of dangerous items that they did not yet have a method to to resolve, with three security checks at the entrance.

Xuan Ji could not let go of his sword, so he unknowingly brought the heavenly demon with him into the headquarters. Sheng Lingyuan was forced to be scanned by the security scanner three times in the sword, and his temper nearly erupted.

When Xiao Zheng called, the heavenly demon was in the sword, closing his eyes and meditating. He didn't originally plan to close his eyes, but the fragments of bamboo slips the little demon had a familiar scent that he was quite interested in. He hoped that after the little demon spread out the bamboo slips, he could have a suitable angle to take a look. Who knew that after looking at it for a few lines, he would fall down and sleep soundly.

There may be some connection between the master of the sword and the original sword. As soon as he fell asleep, a strong drowsiness quickly came from the sword body, forcing the demon in the sword to take a nap.

Xiao Zheng's call not only interrupted Xuan Ji's nightmare, but also woke up the heavenly demon in the sword. Upon waking up, Sheng Lingyuan felt cold in his heart. Because this sword body was like a top-notch cosy resort, it was too comfortable. After staying in it for a while, his sea of knowledge had already calmed down, and the unbearable pain from the Yin Sacrifice backlash had almost completely disappeared.

There was something strange about this sword body.

Sheng Lingyuan hated to look at beautiful things. Anything that did not bring pain, or even made him feel comfortable, would make him vigilant, because temptation often hides traps. The last time he was awakened by the Yin Sacrifice ritual, Sheng Lingyuan was in a daze and didn't understand what the summoner was saying, but the resentment and killing intent in the words were clearly visible. He could roughly guess what was going on.

So who trapped him in the sword this time?

The master of the sword, the little demon himself, was the most suspicious. Although he always looked like he knew nothing, and even showed his heartbeat and breathing, there was a dark spirit beside his bed. Did this kind of pure-blooded demon really have no suspicion at all?

What is his purpose?

Xuan Ji didn't know that he was being plotted about by the sword in his hand. As soon as he entered the isolation room, before he had time to greet Xiao Zheng, he saw several people pushing a low-temperature cooler box quickly passing by him.

"Who is this?"

"A field agent. When looking for the boy, he was on the front line," Xiao Zheng stepped forward, "After coming into contact with the boy, several frontline agents have similar 'sudden change of sex' symptoms, but they are all manifested in some small things. If it weren't for the Mirror Flower Water Moon Butterfly incident that made everyone in the bureau uneasy, these symptoms might have been ignored. The consequences can be imagined–it takes about fifteen to thirty days for Mirror Flower Water Moon Butterfly to spread from infection to death. We have secretly isolated all the people who have been in contact with the boy in the past month–come and see."

Xiao Zheng said, while leading Xuan Ji into a room with a "danger" sign on the door. In the middle was a glass cover with three layers inside and three layers outside. Inside the cover was a butterfly, very small, about the size of a fingertip.

"This butterfly was taken from the boy and is still alive."

There was a magnifying glass on the glass cover, which was convenient for observation. Xuan Ji had never seen a Mirror Flower Water Moon Butterfly, so he went closer. He saw that the butterfly was shining with five-colored fluorescence, and there was a small face on each of its left and right wings. Looking closely, the "face" could even move. First, there was a pair of smiling faces. As soon as Xuan Ji approached, the "smiling faces" disappeared. The face on the left wing of the butterfly changed to fear... and the face on the right wing was crying.

"Did I scare the butterfly to tears?" Xuan Ji wondered in his heart, "Am I so ferocious?"

Before he could see clearly, the butterfly's wings flapped quickly in the glass cover, hitting the four walls repeatedly, and then suddenly disappeared.

Xuan Ji unconsciously leaned back.

"It's just invisible. Don't worry, it can't get out of the sealed box, it's still inside." Xiao Zheng paused and looked at Xuan Ji with a frown, "But usually Mirror Flower Water Moon Butterflies only become invisible after infecting humans. Turning invisible outside of the body has never happened before. Why did it become abnormal when it saw you?"

"In ancient times, there were closed moons and shy flowers, sinking fish and falling geese," Xuan Ji touched his face, "How about it, Director Xiao, do you think my flowery moon looks were enough to make the butterfly a little shy?"

Xiao Zheng: "..."

Why didn't the eighty-odd thunderbolts split this thing up?

Xuan Ji found a chair and sat down: "What's the difference between this special butterfly and the ones that have been 'sterilized' before?"

Xiao Zheng opened his laptop and released an enlarged photo: "You see, the one on the left is the butterfly separated from Bi Chunsheng's husband's body. Look closely, there are three black lines on the butterfly's abdomen - the one on the right is what you just saw, there is nothing on the abdomen. According to historical records, these Mirror Flower Water Moon Butterflies were sealed by some ancient special masters. With fewer and fewer special people in the later generations, it was difficult to keep these dangerous items, so they were handed over to the bureau. We guess that when the ancients first sealed the butterfly eggs, they may have done something special to ensure that they would not spread in the crowd after infecting humans."

Xuan Ji: "What is the transmission method of this special butterfly?"

"It looks like it's a contact transmission."

"Great," Xuan Ji gave a thumbs up and said dryly, "Zombies in a biochemical crisis still have to take a bite – have you checked the butterfly eggs that Bi Chunsheng stole?"

"The Research Institute is simulating an emergency hatching in a human environment to test whether these butterflies have reproductive ability," Xiao Zheng said, "The result has not come out yet."

"What about that little mustache? The last sacrifice, what about the butterfly on him? "

"The last sacrifice, Ji Qingchen, was shot in the head by a mithril bullet, and the butterfly on him was also killed by the bullet, so it can't be confirmed."

"That's troublesome," Xuan Ji leaned back and said softly, "I don't know whether to hope that the investigation will find a problem or not. If it is confirmed that the larvae used by Bi Chunsheng have mutated, then... it's better that the butterfly on the child was released by her, otherwise it's over."

Xiao Zheng was scared by his midnight ghost story.

"The things that Bi Chunsheng does have a time limit, clues, and traces that can be followed. It's not a problem if it takes a lot of work to investigate. But if the butterfly on that child's body was infected from elsewhere, then... who gave it to him? Before it was transmitted to him, how many people were infected? Is it possible that this thing is already spreading widely in the crowd - maybe now everyone in the world, except for the two of us, has become a walking corpse controlled by butterflies... Maybe even we are butterflies, but we just don't know it yet, and we're still playing the game of "cops and robbers". As Zhuangzi said, 'Am I a man who dreamt of being a butterfly, or am I a butterfly dreaming that I am a man?'."

Xiao Zheng's face turned green from what he said: "Dreaming my ass, shut up!"

"Director Xiao, let's embrace the optimistic spirit of revolution and think rationally," Xuan Ji slowly shifted the tone of the conversation. "Nothing in this world is new. If there is a possibility of a large-scale butterfly infection event, it must have happened before in the 5,000 years of our history. It wouldn't have waited until now to happen to you. And you are not the chosen child, either."

"Get out!" Xiao Zheng first frowned and then slightly wrinkled his brows, hearing the meaning of the words, "Slow down, what do you mean?"

Xian Ji said: "Have you ever thought that for this species of butterfly, been an 'eunuch' is the norm?"

"You mean that these butterflies may not reproduce sexually..."

"I mean that these butterflies don't reproduce at all."

Xiao Zheng: "Don't talk nonsense, how can there be animals that don't reproduce in the world..."

"Yes, there are," Xuan Ji retorted. "Isn't that what mules are for? Young master, you don't have to worry about farming."

Xiao Zheng was silenced by him.

"I suspect that these butterflies, like mules, are the 'wisdom' of our ancestors - Comrade Xiao Zheng, do you really think that the Mirror Flower Water Moon Butterfly is naturally born? If it really is like that, what is the difference between the human brain and the pig brain for parasites, why does this thing only parasitise humans?"

Xiao Zheng shivered, not knowing what he was thinking.

Xian Ji pointed at Xiao Zheng's chest vaguely with a smile: "Monsters, demons, ghosts, and strange creatures, which one is more vicious than human hearts?"

As he spoke, he used the back of his index finger to rub back and forth on the blade, his fingers were dexterous and dangerous, as if playing with fire. The sword was not put back into the "sheath", so it was hung outside, the body of the sword was thick and simple, with only two sharp edges that formed two lines, and the unclean blood stains on it were like some kind of ancient totem, adding a bit of dangerous atmosphere.

As the pain from the backlah subsided, Sheng Lingyuan's senses became more and more sensitive. At this time, he could already feel the sound of blood flowing under Xian Ji's finger skin from the almost imperceptible touch on the blade. The heavenly demon was very patient and not afraid of being touched, but just looking at that small section of blood vessels hidden under the skin, a sense of hunger and thirst that had been separated for thousands of years suddenly surged up, almost making him unable to concentrate on what the two were saying.

He found himself wanting to drink blood.

Sheng Lingyuan calmed down and thought that he should not have had such an appetite before, although his memory was like a broken sieve, completely empty, he didn't think he had this kind of appetite before. He couldn't tell whether he simply wanted to drink blood or was only interested in the blood of this little demon. He savored the waves of heat and burning, feeling it was a bit novel.

At this time, Xian Ji seemed to have sensed the danger, and his fingers shrank suddenly. He said to Director Xiao: "Do you still remember what the Bureau's archives said about the 'Mirror Flower Water Moon Butterfly'?"

Before Xiao Zheng could answer, he recited it himself: "'Mirror Flower Water Moon Butterfly', parasitic organism, first-level danger, only parasitises humans. Larvae and eggs can hibernate for a long time. Once they grow into adults, they no longer have the ability to parasitise new hosts. When they leave the original host or the original host dies, the adults often die within a short time, usually within an hour."

Xian Ji pointed to the glass sealed box behind him - the little butterfly appeared again as soon as he left, quietly lying on the glass wall: "Look at it, it has been taken away from the host for a few days, right? I see that it is still in good shape."

Xiao Zheng took out a crocodile-skin wallet from his pocket: "From now on, I'll give you a hundred yuan for every minute you can speak human language."

Rumour had it that Xiao Zheng was a rich second-generation and his family had a mine, and that he worked not for money, but for self-realisation. It seemed the rumours were true!

"Okay, Dad!" Xuan Ji straightened up upon hearing the offer, and his tone immediately softened. 

Without a second thought, he composed himself, "The reason why people infected with the 'Mirror Flower Water Moon Butterfly' are not easily detected is also due to this aspect - think about it, if butterflies can survive outside the human body and reproduce inside it, what kind of scene would it be? After the infected person dies, a large group of colorful butterflies will fly out of the seven orifices of their corpse. Father, we may have already seen countless horror versions of 'The Butterfly Lovers' live on stage.

Before he finished speaking, a researcher wearing a full isolation suit ran in, panting: "Director Xiao, the test results are out! The half-jar of insect eggs taken from Bi Chunsheng's house are all non-reproductive processed butterflies..."

"So the question is," Xuan Ji stroked his chin, "what is so special about the boy from Dongchuan?"

"We have investigated all of the boy's social relationships, and he has no direct or indirect contact with the Bureau. The only person he has been in contact with in this incident is the last sacrifice, Ji Qingchen," Xiao Zheng said quickly. "Ji Qingchen is nothing special either. He was also saved by Bi Chunsheng. He usually makes money by making videos and live streaming, but nothing decent. He disappears whenever there is an incident. He has been walking around at night and sometimes encounters 'real ghosts'. The carnivorous beast incident he experienced was handled by Bi Chunsheng."

"He is the last sacrifice, so 'nothing special' is already very special," Xuan Ji said. "This little-mustached man has put out more than forty short videos and over a dozen live streams. I have gone through them all these past few days..."

Xiao Zheng was taken aback. He didn't expect Xuan Ji, who seemed like a layabout, to be so meticulous in his work. In shock, he asked: "You watched them all? In just a few days?"

"Yeah," Xuan Ji shrugged inexplicably. "In my spare time. When I'm taking a bath, going to the toilet, eating... When I eat alone, I also 'eat streams'. What do you use to accompany your meals?"

Xiao Zheng: "Books."

Xuan Ji was also shocked: "Are you sick?"

The internet-addicted youth and the iron-blooded veteran looked at each other, both feeling that the other was incomprehensible.

Director Xiao needed him, so he had to temporarily agree to disagree. He asked: "What's wrong with his videos?"

"Most of the content in these forty-plus short videos are him solving 'paranormal problems' for others. He talks vaguely, and it's obviously a swindler's trick. A group of people follow him regularly, and they tell others how the 'master' saved them.

"Is that what they call 'network water army'?"

"It's not necessarily. The narrators vary in level, and each person has their own unique version. If it's a water army, the water is too real and sincere. Although the versions are different, the experiences they tell are similar—they encountered a master somewhere one day, the master calculated that there was a disaster, they didn't believe it at first, but after going back for a few days, they were 'possessed by a lonely ghost', with symptoms of 'clear mind but body out of control'. They desperately sent out a distress signal, but their family couldn't understand it, and in the end, it was the master who saved them. How about it, does it sound familiar?"

Xiao Zheng pondered for a moment: "You mean that Ji Qingchen might have come into contact with the Mirror Flower Water Moon Butterfly or something similar before?"

Xuan Ji narrowed his eyes and smiled, looking like a dandy without a backbone. He raised his sword to shine on his face, then glanced at his watch and took five hundred yuan from Xiao Zheng's wallet without hesitation.

"Five minutes and twenty seconds. Since we’re friends, I won’t count the twenty. Get the plane ready. I'm going to Dongchuan to investigate Ji Qingchen's eight generations of ancestors. " Xuan Ji returned the wallet to Xiao Zheng. In front of the researcher, he said nothing, only smiled meaningfully. "Don't worry."

Xiao Zheng was stunned for a moment and suddenly understood his meaning - rest assured, if this was the only butterfly mutation event, as long as it was investigated, the impact could be minimized and it wouldn't be a big deal.

For some reason, Xiao Zheng was not relieved, but instead felt a lump in his throat.

Xuan Ji picked up the heavy sword and left, and the person in the sword was still guessing the words he didn't understand: "Prepare what plane?"

In the Bureau, everyone was in a panic due to the self-investigation, and the Aftermath Department was so busy that they wished they didn't exist.

When Xuan Ji entered the office, he felt like he had stumbled into a botanical garden - everywhere were freshly cut green luo leaves, packed in plastic mineral water bottles and hung in a row in the corner of the wall.

Luo Cuicui explained nervously: "Leader, when I'm nervous, my fingers and toes will grow crazily, and I can't control it, so I have to cut it off... Uh, do you have any instructions today?"

The green was certainly eye-catching, but when he thought that some of them were grown out of Old Luo's socks, Xuan Ji felt that the whole office was filled with a strange smell, and his feet stopped and he stepped back: "Luo Cuicui, Ping Qianru, and... uh... forget it, I'm not familiar with them. You two find someone else and come with me on a business trip to Dongchuan. Other comrades can take care of the office when they are not busy."

The staff management manual of the Aftermath Department had some rigid regulations, such as when the number of people in the business trip team was not less than four, the department's special plane could be used to save costs. Since Bi Chunsheng was not here, a young man in a hoodie was temporarily called out to make up the number. Thirty minutes later, he, Xuan Ji, Luo Cuicui and Ping Qianru got on the plane together.

The man in the hoodie was called Yang Chao, in his twenties, with eight eyebrows, a neck that seemed shorter than normal, and a face of sorrow at a young age. He was carrying a stack of books.

"This is our department's little Yang," Luo Cuicui introduced, "he is especially good at memorizing books, knows everything, you can ask him many things, faster than getting documents from the Bureau."

Before Yang Chao could greet Xuan Ji, he sneezed a few times, making his facial features look like a pig and a dog.

Xuan Ji: "Uh... If you’re not feeling well, don't force yourself, it's not an issue to swop with someone else."

"It's okay, Director, I have rhinitis, and I'm prone to illness when I'm nervous and anxious." Yang Chao took out a wrinkled mask from his pocket and put it on, and said in a muffled voice, "I can do it."

Xuan Ji was not very relieved, feeling that this person was not very reliable, but he hesitated for a moment and still said nothing - let's go, after all, it's just to make up the number, and it's better than summoning a big demon.

"Why do you bring a book on a business trip?"

"To review for the exam," Yang Chao answered honestly, "in case I pass the exam, I have to resign, so I want to save some money. Our department has allowances and meals on business trips, so I can save one day's meal expenses. Thank you colleagues for giving me the opportunity."

After listening to his thrifty words, Xuan Ji unconsciously thought of his bank card balance, and couldn't help but feel sad: "Ah, let's go then."

"Qianyang." Thought Sheng Lingyuan, he "looked" from the sword, just as Yang Chao glanced this way, as if he had met the sword's gaze, he was startled and sneezed almost enough to make the plane fly. This amused the great demon, who remarked, "Despite having diluted bloodline, your perception is quite sharp."

At this time, the plane began to announce takeoff.

Sheng Lingyuan was still thinking whether "takeoff" had any implied meaning, when the plane had already accelerated along the runway, and with a numbing roar, it left the ground and pulled towards the sky.

The heavy sword that was not properly placed fell down due to inertia, and Xuan Ji subconsciously stretched out his hand to catch it. His palm was just on the sword blade, and this sword that was pulled out from his back cut his hand open - blood flowed down along the sword groove.