Han Dong's insane laughter was not intentional.
He simply hoped that his diversion plan would succeed in turning all of the Other Resident's attention on him... So, he could make use of the tactics he had set up outside.
Han Dong was lying on the dissection table, a smile on his face.
"In the full sense of hypnosis, we are drawn into the illusion through the use of 'gaps' and 'focused nerves', and then led astray by various strange phenomena, causing us to become deeper and deeper within the illusion.
The progressive method led us through the billboard → ring road → motel → magic underground door → dissection room → female corpse.
We are dragged deep into the illusion, by misleading us with Yu Wu's words, and making everyone focus on [the Female Corpse].
In this way, the misleading illusion was formed.
