The Underworld

The Underworld is an area in the anime Sazeku-Ba! that has been visited by the main protagonist, Tadashi Sakura. This place is the home of Hades, an evil overlord who takes pleasure in watching people suffer.

Whereabouts
The Underworld is approximately 684,079,984,243 kilometers below Hell. In the Underworld, the whole place is dark and hardly any light exists there. There is the Fountain of Youth there, as well as Cerberus' Cage, Hades' Domain & the Never-Drink Holy Water. As well as Hades living in the Underworld, Shou Asazuna lives there, along with Hades' pet, Cerberus and the Dark Lord. This place is also connected to Hell's Bowl and the Afterlife.

Significance
The Underworld plays a big part at the time of when Tadashi was dead. He fell into Hell and was later banished into the Underworld. There, Hades beat him up a little bit before sending him to Cerberus' Cage. There, Tadashi struggled to stay alive until King Eerie saved him.