How Old Is Milim Nava in Naruto

Let's clear the air right from the start: Milim Nava, the incredibly powerful and deceptively adorable Dragonoid Demon Lord, does not actually appear in Naruto. While both franchises are titans in the anime world, Milim is a core character from a completely different universe: That Time I Got Reincarnated as a Slime, often shortened to Tensura. It's easy to see why someone might wonder about her presence in another popular series....