Purgatory is an asomatous location, existing parallel to the corporeal world and can be found only by the deceased. It serves as a major backdrop throughout the series.
Purgatory is established as a holding place and home for reaped souls before they either ascend to the afterlife (if their virtues outweigh their vices) or live out the rest of their existence in the river Styx (if their vices outweigh their virtues). When human souls are first reaped by ghosts, it is required for the ghost to ask the human soul to choose between living in purgatory and reaping souls themselves our haunting the Earth as ghosts. If the former is chosen, the ghost eats the soul, and all of the souls obtained will become inhabitants of purgatory once a new chief priest is chosen and the cycle continues. In either situation, the soul being reaped cannot change his or her mind at any time once a decision is made.
In purgatory, there is only one building, fashioned like an enormous mausoleum which houses Pluto and Persephone, dorms for soul-reaping ghosts, chambers and corridors for priests and burial chambers for deceased priests. Beyond it is a lush and vast open field, with gardens, forests, mountains and even beaches.
Besides being a holding place, purgatory also serves as a home for ghosts whose souls have been reaped by previous ghosts, and dormitories are available for individual ghosts and soul-reaping teams. In addition, ghosts can travel to and from purgatory to Earth freely, even for matters irrelevant to soul-reaping missions.
Although only one chief priest of purgatory can be chosen per term, all citizens are required to reap souls to pay off their Earthly debts and to repopulate purgatory once a new chief priest is chosen; however, members of the Ministry of Thanatos do not fall under this requirement and reaping souls is an optional task for them unless they choose to secede. 13,060 souls for each ghost or soul-reaping team is considered a desired amount, and once their remaining amount is whittled down to the hundreds, they are eligible to participate in meetings with Pluto and Persephone over their qualifications for becoming chief priests and are given courses on how to perform their future tasks properly. Ghosts and soul-reaping teams are recorded on a leaderboard along with the respective amount of souls collected, making forms of gambling a la sports betting a common practice.
Once the objective is met, a public ceremony is held, and the team (or individual ghost, with at least one other ghost directly affiliated with them accompanying them as a witness) and current chief priest appear before Pluto and Persephone to regain their human bodies and become purgatory's new chief priests (or co-priests, as is common in teams). A single request, or wish is allowed to the ghost or individual members of the team as a reward for their efforts, although anything deemed inappropriate by Pluto and Persephone (such as a wish explicitly regarding the death of another individual for superficial reasons, for example) will be denied, and the ghost will be encouraged to make another, less controversial wish. After this, the current ghosts populating purgatory relocate into the afterlife or Styx accordingly, and the current ghost, witness, and/or soul-reaping team regain their physical bodies, and the souls they have collected will repopulate purgatory, as well as the souls collected by previous ghosts, regardless if they are involved in becoming chief priests. Ghosts who regain their human forms cannot ascend into the afterlife.
- Kleinod and Weltraum often refer to purgatory ironically as hell, and Kleinod also describes it as "less like purgatory and more like a psychiatric ward for dead people". Occasionally, the two compare purgatory's structure to something akin to that of fascism.
- It is implied that purgatory has no solid origins, and it has existed since the beginning of time. This is shown via flashback where Pluto's soul travels to the mausoleum following his assisted suicide, albeit a dark, empty void.