The Oni are spirits that can only temporarily take a physical form.
They often appear in rooms that they couldn't possibly have gotten into if they're entirely corporeal beings. This also explains why they chase you for a few rooms then disappear for a while. Once they've been Oni for a while; they turn back into spirit form to gather their strength or spiritual power and wait for their chance to become physical again. The Ao Oni are completely sensible, even benevolent creatures, however...
The scent of humans drives them mad. They lose all control of themselves and can't help but chase them down.- Crom Oni, while a fan made game does have a group of Oni's that are completely civil, friendly, and passive. They even let you play a minigame if you have the Kitchen Gun.
The Ao Oni is the creation of human suffering
Wandering around the house, you find prison cells, and even later a strange altar and weird hospital beds. What if some family had a deformed baby, and they kept the baby hidden from the world, and imprisoned it as it got stronger and stronger. The fact that dead things in the house become Ao Onis as well is because of all the suffering the main Oni went through, which turned it from just a weird defect into a supernatural monster. The Oni are creations of Tommy Wiseau.
- Compare the poster for The Room
◊ to the well known Oni.
The Oni evolve.
- When your friends change, they turn into a being that looks like the original monster, but with their hair. Takuro keeps his human for a while and only changes when you go into your menu. Other versions of the monsters are deformed beyond recognition of humanity. Now, unless they are demons or perversions of other animals, maybe the longer a human is an Ao Oni, maybe the more their body mutates.
The Ao Oni remember their pasts.
- Maybe the Ao Oni remember who they are. Takuro was normal even after it was obvious he was caught. He also recognized Hiroshi. He may just not had changed yet, but it's possible he knew him and was using that to get close to him. This is a bit of Fridge Horror as the Ao Oni seem to want to eat humans and make them like them. They could share some sort of Hive Mind and be unable to stop themselves from killing their friends or they just no longer care.
- Or, maybe they do care... enough to want their friends to enjoy their new form with them.
The Ao Oni can choose their form.
- This goes with the evolution and the "remembers their pasts" theories above. Maybe the Ao Oni are sapient enough to choose their form. Takuro looked human, but obviously wasn't. Maybe they learn to control their bodies and can eventually turn into other forms like the ones locked up in the basement.
The Ao Oni are the earliest Titans.
Think about it. They are big but not too big and we see humans turn into them when they die. The Ao Oni are the familiars of a particularly horrific and powerful Witch, and the mansion is her Barrier.
- They share the Witches' distinct gimmick of having an artstyle that clashes entirely with the aesthetic of the rest of their respective medium, and the mansion they inhabit exhibits Eldritch Location tendencies not unlike a Witch's Barrier. Their assimilation plot angle has been proven to be possible via Elsa Maria, whose familiars are stated to be the aggregate of the people she "saves." The only question is what kind of Witch would spawn familiars that are not only so dangerous, but also come in at least five variations...
