Kaikoku and Zakuro reveal that while the others were playing Stage 3, the two of them snuck to Floor 51 after discovering that the entire city is completely vacant save for the players. However, as they were found out, Paca sets an S-level difficulty stage for them to conquer next as punishment, called "Exterminate the Mimicry Man-eaters" and sealing them within the Genome Tower. As the first Mimicry Man-eater appears in their room, it splits the group into two, with plans to regroup and meet at the basement food storage room. The monsters multiply extensively in their chase, frequently imitating the appearance of their comrades to fool them, but the group successfully manages to meet as the sun sets...