(I went to like this and I down voted oop)
Oop, all g lole
They explained it a few chapters ago, something about a blessing or whatever if they make him laugh, he's some type of miracle. From my understanding it's not even guaranteed to be a young master, they only.gendered him once he appeared, meaning the baby can appear as either a girl or boy. IIRC they have to make him laugh within a certain time period or something to receive a blessing. You can run a couple chapters back (sometime after the final battle) and it'll explain.
But where did they come from? Why so out of nowhere, who are they? That's super vaguw
Well he's a miracle, there's really not much else to a miracle, miracles just don't make sense. This is a fantasy world after all too so... yeah. You'd probably just have to go back and find that chapter, I can't remember which one it was.
Who tf is the younger master LOL? Like. Am I the only one who was confused when he showed up, like who is he? Why do people care did he just show up?