Dystopia: The Tree of Language was about witchhunting especially online, what if this time is about "labels" given to use by society, since the signs says 怪物(monster) 朋友(friend, fake or real)
the mask was probably positioned behind that rock and yoohyeon’s resting on the fallen pillars seen in the mystery code, sua’s wielding an mysterious and seemingly cursed sword,, i cant make up what are engraved on it though