This is the main village setting where Aella, X, and Delta live. X has his own house that Aella usually breaks into to be with X. Delta, being a higher ranked slayer, lives in the giant tree. Delta protects village heads from within there.
This shows how a battle would go between them. Delta goes power crazy and summons her powers to attempt destroying Aella. X is just trying his best to get out alive. Aella wants X to fight by her side.