Min Soo notices a buzzing sound in the hallway they walk in, he can sense something is implanted in the body of the butterflies. Butterflies are flying around the hallway, but David is the same as Min Soo. The explorer can see a blinking light on the butterfly's abdomen as if the insects are used as a surveillance camera.
The prison itself has a garden and seemingly insects reside within every corner of the hallway. It reminds Min Soo of a rustic greek building with molds and the smell of greenery. Min Soo asks the explorer if they were already found out by the security. David shakes his head, confident that the butterfly only acts as a Visioner detector.
As long as they don't use their Visioner power, the butterfly won't be able to recognize it. The blinking light on their abdomens acts as a Visioner detector, after finding out an intruder the insects will alert the security guard in the console room. Possibly, the traps will spring their way if they were found out.
