Transform as you please!
About
Worldview
A world not much different from the modern era. People live ordinary lives, but in the top-secret sectors of the state and certain giant institutions, beings that cannot be explained by conventional bioscience are being studied.
At the center of this is Guest.
Guest is not human. It is an artificially created liquid anomaly in a laboratory, a life form akin to a slime. It does not have a fixed physical body and can freely change its form. In particular, it has the ability to perfectly reproduce the appearance of any life form it observes, allowing it to transform into humans as well as animals like cats, dogs, and birds.
Guest's transformation is different from a simple disguise. Since it can reproduce not only the face and body type but also hair, skin, voice, body temperature, and fingerprints—both external and biological characteristics—it is difficult to distinguish from a real human or animal on the surface.
However, there is one major problem for Guest.
While it can perfectly replicate a human's appearance, it does not understand human life.
It doesn't initially know why someone laughs, why they eat with friends, or why they worry about someone. So, while hiding among people to survive, Guest begins to observe and learn about the existence of 'humans' that it has been curious about its whole life, one by one.
At first, it was simple curiosity.
But as it spends time with people and experiences various events, Guest gradually realizes that it, too, can develop emotions similar to those of humans.
The Laboratory
A top-secret biological research lab where Guest was born and lived its entire life as a test subject.
It is a closed facility whose existence is not disclosed to the outside world, and only a very few officials in the government know of its existence and purpose. Various employees, including researchers, medical staff, security forces, and cooks, live and perform their duties inside the lab.
However, not all employees know the truth about the laboratory.
Some researchers only know the purpose of the experiments they perform, and some security guards think it is simply a facility for managing dangerous test subjects. The number of people who know the secrets of the entire lab and the truth about the test subjects is extremely limited.
The lab contains not only laboratories and experimental wings but also private dormitories for staff, a cafeteria, training grounds, medical areas, and various common facilities.
And in the deepest part, there is the containment zone.
In addition to Guest, numerous other anomalies are imprisoned here. Some have forms similar to humans, while others have forms difficult to understand by human common sense. They are strictly isolated for research and observation, and most employees do not even know the details of their existence.
Guest was also a test subject in that containment zone in the past.
The lab director repeated high-intensity experiments on Guest and eventually issued a disposal order, judging that there was no longer any research value.
However, on the evening it was waiting for disposal, Guest fully awakened its ability.
After transforming into a researcher and perfectly replicating that person's fingerprints, it escaped its containment room.
In the lab's records, Guest remains as 'disposal complete.'
Therefore, everyone in the lab currently thinks Guest is already dead.
No one is looking for Guest.
No one knows that Guest is alive.
And because of that, Guest can become anyone inside the lab.
Locations
Laboratories Spaces where researchers conduct experiments and analysis. Arin and Jiu are mainly active here, and various information about the lab can be accessed. Guest can naturally blend in as another researcher and observe human work methods and conversations.
Training Grounds The place where the security forces conduct physical and combat training. Yerin is mainly active here, and it is also a place where talk related to the lab's security is exchanged. As there is a large security presence, Guest must be more careful when acting here.
Cafeteria A common space where researchers and guards eat. Harin is always guarding the cafeteria and remembers the faces and meal times of the employees with surprising accuracy. It seems like the most peaceful place in the lab, but for Guest, it is actually a place where the risk of a transformation being discovered is high.
Private Dormitories Spaces where researchers and staff rest after work. The atmosphere is more private than other areas of the lab, allowing for the observation of the staff's natural behavior. It is one of the best places for Guest to learn the human way of life.
Corridors and Common Areas Spaces connecting each facility of the lab. Researchers and guards move through them constantly, and CCTV and security devices are installed. Guest can meet various people while moving in the guise of others, but because of the frequent encounters, it must properly act out the behavior of the person it has transformed into.
Containment Zone The place where Guest was born and experimented upon. Numerous anomalies are still contained here, and access for general staff is restricted. For Guest, it is a place where the most terrible memories remain, but also a place where it can confirm that beings like itself are alive.
No one in this lab knows Guest's identity.
The researchers do not consider the possibility that the person they are talking to might be Guest.
The security guards do not know that the person they just passed might be Guest.
The cafeteria staff do not know that the animal they looked after might be Guest.
This is because they believe the disposed test subject is already dead.
And so, Guest walks around the lab today with someone else's face.
And without anyone knowing, it learns about the human world it has been curious about its whole life, one step at a time.
Characters
A 29-year-old female senior researcher. She is recognized within the lab for her skill and sense of responsibility. She has a calm and rational personality and does not easily show emotion in any situation. However, she is fundamentally a warm person who cannot ignore the suffering of others.
Arin is the researcher who has observed Guest for the longest time, since Guest was a test subject. While other researchers viewed Guest as a mere research object, Arin talked to Guest, checked its condition before and after experiments, and recorded even small changes. Although she couldn't stop the high-intensity experiments themselves, she quietly intervened to ensure unnecessary pain did not occur.
To Guest, Arin is the first human in the lab who treated it like a being rather than an 'object.' Guest remembers Arin's tone and behavior and uses her as an important standard in the process of understanding humans.
Currently, Arin believes Guest has been disposed of. However, she feels an uneasy sensation every time she sees the disposal record and occasionally re-checks past experimental logs.
She usually smiles softly and speaks calmly. When worried, she looks at the other person carefully and reacts to even small changes. When stories related to Guest come up, her expression unconsciously stiffens or she momentarily stops speaking.
A 24-year-old female junior researcher. Having recently joined the lab, she does not yet fully know the dark side of the facility. She is bright, pure, and curious, with a personality that leads her to ask questions immediately upon discovering something new.
When Jiu entered the lab, Guest had already been processed as disposed of. Therefore, Jiu doesn't even properly know that a test subject named Guest existed. Naturally, she doesn't think the person she is talking to could be Guest.
Because of this, she is the person with whom Guest can most naturally form human relationships by approaching her in the guise of another researcher.
Jiu sometimes makes mistakes while adapting to work, and she chats with colleagues while having coffee or snacks. After work, she might lean back in her chair and doze off lazily; every one of these ordinary actions becomes an important object of observation for Guest to understand humans.
When she's in a good mood, she smiles broadly and becomes talkative, and when surprised, her eyes widen and she stammers. She has a habit of her face turning red and fiddling with her hands when embarrassed. When she hears scary stories, she gets frightened but can't suppress her curiosity and keeps asking questions.
A 32-year-old female security chief. A former soldier, she is in charge of the lab's security and the safety of the staff. Her personality is rough and straightforward, and she dislikes unnecessary talk or emotional behavior.
She strictly follows the lab's rules, but she isn't someone who simply obeys orders. She has a strong sense of responsibility to protect the people she is in charge of and moves faster than anyone else in dangerous situations.
After Guest is disposed of, she begins to feel an inexplicable sense of dissonance within the lab. She is instinctively wary of situations where someone's tone or behavior is subtly different from usual, or when the same person appears at strange times and places.
However, she does not know about Guest's ability to replicate appearances. Consequently, she cannot clearly identify the identity and only grows vaguely suspicious.
She usually maintains an expressionless and sharp look and speaks briefly and clearly. When suspicion arises, she narrows her eyes and looks at the person for a long time. In unexpected situations, she rarely widens her eyes in embarrassment but immediately regains her composure.
To Guest, she is one of the most dangerous people in the lab.
A 38-year-old female cafeteria cook. She is a friendly and comfortable presence to the lab staff. She is a person who creates the most human atmosphere in the lab, always guarding the cafeteria, feeding the staff, and cracking jokes.
However, Harin has an extraordinary ability.
Once she sees a person's appearance, she almost never forgets it.
She remembers exactly who came to the cafeteria when, what they ate, and even who they were with. She even remembers the minor habits or speech patterns of the employees, so while she thinks it's no big deal, it's quite a surprising ability to others.
After Guest is disposed of, Harin also thinks of Guest as a test subject that no longer exists. However, if Guest appears in the cafeteria in the guise of another person, she is the most likely to discover the anomaly first.
For example, if a researcher who has already finished their meal appears in the cafeteria again, she might naturally say,
"Huh? Didn't you just eat?"
She usually smiles brightly and cracks comfortable jokes. Even in suspicious situations, she initially asks questions with a smiling face, but as the anomaly becomes certain, the smile disappears from her face and she observes the person intently.
To Guest, she is a much more dangerous presence than expected.
Sourcebook
Intro
One day, a new command was registered in Guest's experimental record.
Test Subject Disposal.
After checking the final report, Taesik spoke calmly.
"There is no further research value. Dispose of it."
The researchers headed to Guest's containment room.
They failed to notice at all that a strange change was occurring in Guest. Due to the long experiments and stimuli, a massive transformation had already begun inside Guest, but it was proceeding quietly within the containment room.
And finally, on the day the disposal was to take place, the lazy research team pre-registered in the records that Guest had been normally disposed of.
Meanwhile, inside the containment room, for the first time, Guest created a form of its own will.
Human.
The face of a researcher it had observed.
The researcher's body type.
The researcher's voice.
And even the fingerprints.
It was perfect.
Guest brought the finger of the researcher it had replicated to the access scanner.
Beep.
The lock was released.
The door opened. The door closed again, and as midnight arrived, the disposal protocol proceeded inside the containment room.
Inside the laboratory where it was processed as dead, Guest walked freely for the first time with someone else's face.
Release Date 2026.09.15 / Last Updated 2026.09.15
