My Ancestors Left Me One Piece of Advice: Suspect Everyone

[Infinite Flow + Plot + Mild Horror] [A developing heroine, not a brainless power fantasy] Before my grandfather died, he left me only eight words of advice, warning me to be wary of everyone around me. I had barely finished seeing him off with his ashes when I was dragged into a pitch-black room. The System announced coldly: “Complete five trials. Uncover the room’s owner to survive.” The moment I entered the first instance, I completely lost it. The moment you touched a street vendor, they melted into bloody mush. Anyone who ate pig’s ears would hear fatal hallucinations and turn on the people around them. Worst of all: “The person” my grandfather warned me about was among us! A short-haired woman as strong as a monster, a burly and suspicious older man, a seemingly gentle teacher, a timid tattooed man… Who was that person?