His inferiority complex AND his indecisiveness.
And we had to sit there for 100+ chapters before he finally got his act together!
(Not that I mind, I really liked it)
Okay, my brain is telling me there are too many details that annoy the heck out of me.
1. Did none of the guards/wizards do a headcount when the children got summoned? Or is it that when the "Hero" appeared, they said "WE FOUND HIM!" and didn't bother with anyone else's statuses? But I will...
So the slime basically sucks out everything from within to divide itself.
If she wasn't immortal/indestructible, she would have probably gotten her insides drained and dry of her mana. Transforming this... Breeding documentary quite more gruesome...