Demo Crispys are enemies that showed up in the Lost in Vivo Demo, and in special occasions, the full game.
The Demo Crispys appear to be boxes full of flesh that levitate.
In the full version of Lost in Vivo they do a lot of damage, they can also take a lot of damage so they are a pretty big threat.
Not much is known about these enemies since they were cut early on. But they were made at the time when the game was about being lost in a living body.
They appeared in the sewers in the demo because that was the only area made at the time, but in the main game they appear in The Gallery of Light and in NG+??? which is the randomized enemy mode, this allows them to appear anywhere in the game.