Was it the same Demon King on the throne back when Frieren met her master, or did new Demon Kings pop up to replace their predecessors following the time until she partied up with the hero.
That build up was so satisfying... no bs, no nonsense, just pure raw power and just like that... you kill yourself because you’re not a match for Frieren
Damn. If you think about it, she could have defeated her in almost any other way. Instead, Frieren prefer to wait until Aura tried to submit her and then have Aura kill herself...
For an emotionless/apathetic being blessed/cursed with eternal youth: that's pretty fucking vindictive and savage.