Empress Necklace

Geofront. An underground world in which reside all those excluded from society. Komugida wants to leave the basements of Geofront at all costs by enrolling in a university on the surface, but eventually returns to live underground to work as the private teacher of a young boy with divination gifts, named Theo. His father, Nagasa, is according to him a "mafia killer"! A life altogether ordinary for the inhabitants of these undergrounds, who try as best they can to survive in a hostile environment excluded from the surface of the Earth.

Note: Volume includes an additional, unrelated one-shot.