Location Theories

Apartments

  • It can be implied that the blocked room is actually the interior of Sabitsuki's childhood home.

Decaying Art Gallery

  • It is quite possible that Sabitsuki drew these herself, this seems evident as the Hovering Screens appear both in the dream world and in the pictures.
  • The fact that the drawings feature eyes, screens, or both leads to the theory that perhaps Sabitsuki was under an almost constant surveillance which if considering the prior hospitalization would make sense.

Flesh Walls

  • It's been speculated that this area may very well be Sabitsuki's own body with either the black haired girls being the cancer or her immune system.
  • It should also be noted that one of the areas in here was thought to be uterine shaped which lead to the theory of her perhaps having some kind of cancer or disease affecting her uterus. The doors also look rather vaginal as well

Heart Tile World

  • It's almost certain this area represents the heart and can be even further proven by the next area having heartbeats everywhere.

Hell

  • This may be what Sabitsuki has been taught to or came to believe about what would happen to people who commit bad deeds in life.
  • Given that the guillotine was inside the prison, speculated to be Sabitsuki's hospital, and close by is the Machine effect, this could symbolize Sabitsuki's emotional death from being bedridden for so long, or continuously "flowing" and repeating the process.
  • The fisherman is likely a reference to the River Styx ferryman, or how a fisherman is used for teleportation similarly in Yume Nikki.

Industrial Snow World

  • The industrial world could be or near to where Sabitsuki grew up, at the same time the smoke (or, rather, the industrial chemicals causing or in said smoke) could be the cause of her illness. Support for this theory is the young Sabitsuki ghost that wanders around the area.
  • Alternatively, it is theorized that the factories and the snow is really a mass crematorium and the snow is really ashes.

Microscopic World

  • This world may be a result of Sabitsuki learning about Cells and how a disease affects them. Perhaps as a result of trying to learn more about her own illness she stumbles upon the field of microbiology.

Nexus

  • It supposedly represent's Sabitsuki's current state of mind, due to its ever-changing nature depending on how far into the game you get.

Neon World

  • The Neon World could be a manifestation of something happy or fun (like music, given the fact the Headphones are found here) that Sabitsuki might have enjoyed.

Plant Labyrinth (Past)

  • It's suspected to be in the past due to the fact that Little Sabitsuki can be found within this world near the entrance.
  • The plant children here could indicate that some kind of herbal treatment may have been used along the way or as another alternative to the treatments as you get there by way of the alleyway hospital.
  • It is possibly a ward of the hospital that has since been overgrown by plants

Prison

  • This area may be how she feels about the hospital, this is furthered by the prisoner that resembles a darker version of Sabitsuki, she may feel as though she's a prisoner at the hospital she was at, also bringing the theory that she was under constant surveillance into consideration may possibly add on to that, also there is a guillotine in the area that leads to Hell, that may be a view on people on dying from the disease, or possible human euthanization, and the Reapers next to the guillotine may represent the doctors that either performed the euthanization or simply took away the dying subject.

Red Body

  • It is possible this area represents a horrid condition Sabitsuki has or had developed

Slum

  • There is a theory that the slum was where Sabitsuki grew up along with Smile.

Sugar Hole

  • This could have been one of the first locations Sabitsuki may have fled to after escaping the hospital.

Sweet Sugar

  • Coupled with the Vomitgirl Area, it's thought that this location is associated with prostitution. Sweet Sugar might be a place where such business could be conducted (i.e "compensated dating").
  • Because of a room named Reminiscence (昔話) in the game files, which has a blood-splattered bed, it can be speculated that Sabitsuki may have been born there, or that a woman was attacked there.
    • Or that, if Sabitsuki (or the Girl) was a prostitute, then she may have had a back-alley abortion or was assaulted there.

Special Areas

Corrupted School

  • When you get to the bottom of the corrupted school Smile will kill you. This could be interpreted as an emotional killing that when Smile took her down to the basement and told her to leave him and his sister alone it was an emotional and social death to her as she's now lost her only friend.
    • Following the theory above, this means that Rust's version is essentially Sabitsuki getting revenge on Smile for what he did to her.

Rust Corridor

  • It probably represent's Sabitsuki's/ Rust's core, due to the final room resembling a body, and Demon Sabitsuki in the room after it.

Vomitgirl Area

  • Like Sweet Sugar, this area is associated with prostitution, especially with the white statues of women in suggestive poses. Likewise, the Girl in Yellow Dress being seen atop a statue is thought to be or have been a prostitute, though, her relationship to Sabitsuki isn't clear (besides that she's speculated to be her sister or mother).
    • Because it takes some tries to trigger an event to get here, it can be assumed Sabitsuki experienced something traumatic and tried to forget/ignore it.