That Time I Got Reincarnated as a Slime: Tensei shitara Slime datta Ken

[KrayZ33]

How was the demon lord introduced but all the other characters not?
introduced as in "this person exists and he has a name, thus he is relevant to the story at some point".


and why I should be interested in them? Because they've shown them - why show them otherwise?
Plus, so far we/I've assumed the hero was Shizu. At least they looked extremely similar in the flashback in the earlier episodes and she was wearing that very unique mask - not sure what else gave it away that she isn't the one other than her saying that the hero, which isn't her, exists. Especially since she used fire magic in it....