This is actually a flashback episode, preceding the events of the series. It highlights the relationship between characters playing huge roles in the story and what motivated them to arrive at the setting. The overarching theme here is longingness for a loved one, or at least, a family. A lot of scenes seem to symbolically refer to this premise, and is heavily implied to have played a part on why some of the casts behave the way they do. The show held back a little in terms of animation this time, but that's given since the nature of the episode requires it. Time to get back to the main narrative for the next one I guess?