The Promised Neverland S02E03 - Episode 3

Emma and the group learn the necessary skills to survive in this world from Mujika and Sonju. The two demons also guide the children toward the place indicated by the pen before going their separate ways.
Back on their own, the children traverse a wasteland in search of a place called "B06-32." When they finally arrive, they find nothing. However, when they input a password in the pen, a map of the area appears, as well as an entrance to an underground shelter. The shelter itself turns out to be a fully equipped facility that provides much-needed rest to the children. But as they live at the shelter, more mysteries begin to present themselves.