Hell was the world where people who had committed grave crimes in life ended up after their souls became Hollows and Shinigami killed them.
Unlike the other three realms, it was an independent world, not created by the Soul King.
Instead, it had arisen of its own accord with the appearance of the three realms: the Soul Society, the Human World, and Hueco Mundo.
If the Soul King died and the other three realms collapsed, Hell would remain completely unaffected, because it was independent and unique.
It was just as when the existence of bad people gave rise to organizations that punished them. Even if Hell's existence had not been the Soul King's intention, he could not stop it. Strictly speaking, Hell's Will was on the same level as him.
So this was a place that even the Shinigami had no right to meddle in. Whether Shinigami or Hollows, anyone who spent too long in Hell would be eroded by its miasma and hunted by the Hell Keepers, beings also known as the Will of Hell!
Once a Hell Keeper killed them, even a Shinigami would be pierced by the Chains of Hell and turned into what was known as a proper resident of Hell.
That meant becoming a Togabito!
But that was nothing to brag about, because... from then on, your life here would be a true existence in Hell.
When a person died, their soul was sent to its homeland, the Soul Society. But Hollows who had been utterly wicked in life could not enter the Soul Society, even if a Shinigami killed them and performed a soul burial. They could only fall into Hell.
Then, as Togabito, they were bound by chains and forced to atone for eternity, becoming beings who could not die. But this... was