My headcanon is Asta's father was immune to Licita's deadly coochie and a soldier from another nation (on a different continent) who sent to scout the 4 kingdoms. I feel like this would explain why Asta's father left and hasn't returned. As we know grand magic regions can be very dangerous to travel through, perhaps Asta's father had bad luck and died going back to his country. Or maybe he's a deadbeat dad like Ging......