Same way I did, I think. Some kind of dimensional gate malfunction. Or fate is being whimsical again. Can't decide which.

[There may be a touch of bitterness at the thought of fate playing with him again.]

They make look young, but any one of the demons or monsters in this hall might be much stronger than they appear. That said, they'll probably leave you alone if you don't pick a fight with them. But you said you train in the Netherworld, huh?