Hell

Hell is an afterlife dimension where evil souls are sentenced to eternal damnation. Hell was first introduced in Episode 1, and has made multiple appearances throughout the series. Hell is ruled by Satan, who determines which sub-layer of Hell a damned soul is placed in upon their arrival. Reapers may temporarily remain in Hell to recover, speak with Satan, or witness a soul being sentenced.

According to Satan, time moves by much slower in Hell than it does in the waking world. This was confirmed when Scarlet asks how long she had been in Hell, to which Brook stated 25 years when in the waking world only 3 days have passed. Going by this information, a single day in Hell is only ~25.92 seconds on Earth.

Appearance
Hell is characterized by its scarlet skies, treacherous terrain, and satanic / demonic imagery such as upside-down crosses and burnt down churches. The soil in Hell is colored a deep crimson red and other geographical features are colored similarly.

The exact appearance of Hell varies widely between the different layers - with the 2nd layer of Hell supposedly being an exact replica of Earth and the 9th layer being a pitch black void where nothing exists. Despite this, the color scheme remains consistent across all layers.

Circles of Hell
There are nine circles in Hell with the punishment in each level growing more severe as the number increases. While the series does take inspiration from Dante Alighieri's The Inferno, the series deviates from the book and instead came up with its own punishments and depictions of the layers.

Circle 1
The first circle of Hell is a large, expansive valley in which sinners are condemned for committing minor offenses such as repeated counts of petty theft or robbery. According to Satan, the only punishment in this circle is simply loneliness, as it is extremely unlikely for two sinners to encounter one another (due to the sheer size of this circle).

This circle was first seen in Episode 8 where Satan sentences a sinner to an eternity of being chased by a snail, as punishment for her stealing over $500,000 worth of snails over her career. This circle was presumably seen again in Episode 18, where Satan pushes the author off a cliff shortly before speaking with Scarlet.

Satan considers this circle to be boring, and remarks that it is barely different to Limbo.

Circle 2
The second circle of Hell is an exact replica of the planet Earth, albeit devoid of any life. Sinners in this circle are placed into varying locations around the globe, as stated by Satan when he starts off a sinner on a freezing cold ice sheet. It is unknown what qualifies a sinner to be sentenced to this level.

Circle 2 made it's first brief appearance in Episode 33, after a short montage of Scarlet and Chase working together to eliminate sinners.

GRAVEWEAVER said that there is probably no wait line for her favorite restaurant in this level, suggesting that the replica Earth is constantly updated as new things are built on Earth - but this may simply just be a joke and not actually a feature of the level.

Circle 4
The fourth circle is a massive graveyard, where sinners are buried into their own graves - while being fully conscious. Sinners who attempt to escape their fate find themselves unable to and are forced to constantly choke down dirt for all eternity. Sinners sentenced to this level are those who have committed less severe forms of murder (such as killing a random stranger).

This circle was introduced in Episode 63 where Liam was sentenced for the murder of an old man. When Satan was asked by Scarlet why he wasn't sent to the same level as Ana, he simply stated that killing a random old man isn't on the same level as killing one's own child.

Circle 5
The fifth circle of Hell is a massive cliff where sinners who were condemned to this level are hung by nooses and feasted upon by crows until their flesh is completely consumed - after which their flesh will regenerate for the crows to return for another meal. Those damned to this level have committed more serious forms of murder (such as killing your own child).

Ana, Liam's childhood friend, was sentenced to this level after the murder of her own terminally ill son. (Episode 11)

Circle 6
The sixth circle is a vast lake littered with crosses and skeletal arms. Sinners are chained up and dragged to the bottom by their sins (as portrayed by living skeletons who pull the sinner down). Serial killers and other violent criminals are sentenced to this circle.

Jordan is sent to this level for the murder of over 10 women, as seen in Episode 3.

Of note: It is unclear whether or not this is the 6th or another circle of Hell. In Episode 63, Scarlet mentions that Ana is in the 6th level, however, in Episode 11 Satan condemns her to the 5th level. This could simply be a mistake on the author's part and intended for Scarlet to mention the 5th level.

Circle 9
The ninth circle is the deepest level of Hell, and is the most severe (and rarest) level that a sinner can be sentenced to. The ninth circle is a form of psychological torment, as sinners in this level are trapped in an all-consuming void with only their own mind and thoughts to accompany them. It's unknown as to what can get a sinner sent to this level, but it has been stated by Satan that corrupt world leaders, perpetrators of genocides, and other heinous criminals are sentenced to this circle (Episode 8).

Scarlet was sent to this level twice during her time as a reaper. It is first seen in Episode 1 during Scarlet's introduction as a reaper (as a threat to what could happen if Scarlet fails to meet her quota or if she disobeys Satan's orders), and has made repeat appearances throughout the series. Scarlet is morbidly afraid of this circle, and her fear of being returned to it has led to multiple mental breakdowns and incidences of Scarlet lashing out with violence.

While this is the deepest layer of Hell, Satan has said that there was one individual who was given a more severe punishment than the 9th circle. Who was given this special punishment and what the punishment was is up for speculation.