This episode gives more information on how the elves actually were reincarnated. A lot of it feels like retelling with bits of Secre's point of view here and there but it connects the past to the present nicely. It also shows that Secre or Nero has been with Asta since he was a baby, so she could have a deeper relationship with him which would also explain why she did what she did when helping Asta fight the Devil, or am I reading too much into it? Overall the episode has a slow pace but acts as a nice filler while they travel home and gives good backstory and character depth