Kamisami no Inai nichiyoubi - ep09

The fourth arc if you can even call it that is a single episode about the origins of the Gravekeepers. That in someway it is also reflecting on what Ai is since her mother was one. Although the main point the the story tries to tell is the pursuit of Scar and trying to find the reason on why she left. That as they go further north as they approach the birthplace of all Gravekeepers Dee leaves because she doesn't like the ominous feeling the place gives off as they continue their pursuit of Scar. That as they travel further north they can't go anymore by car because of all the crater in the ground. That it isn't long after that they see how the Gravekeepers are born as what appears to be lightning strikes the ground creating a crater and out of walks a Gravekeeper. This is where Yuri explains that there are types of Gravekeepers that is why some of them that they see passing by have the same face because they aren't true people.

This ultimately leads them to Scar where she is laying in the crater that she probably came out of, that it becomes clear why she left in the first place. Is that she was struggling with the feelings of what she is and the emotions that Celica causes to raise up inside her. That in the end she choose to abandon her past life as a Gravekeeper to become human. This the only path she could have choose to possible be with Yuri and Celica. This quickly leads us to the fifth Arc the true story behind Alis Color and what he wishes to save.