I-- there's no such Netherworld. Netherworlds are usually inhabited by demons and monsters. But it is possible to turn a human world into a Netherworld.

As for my body? The Sacred Tome grants wishes, if the person who writes the wish has enough mana to power it. If we defeat the Ohm, then whoever gets the mana from that victory will be able to wish everything back to the way it was before they attacked. That means my Netherworld will come back, and so will my body.