The mystery door in Henry’s can clearly be seen here.
That’s if you know it’s a toilet but as we do not know, then it is still a mystery. 
This has already been established here 
x.com
Well i don’t visit the places but when there is a grey area and the bathroom don’t have a toilet, doesn’t seem to be a mistery 
Like which one? Many toilets are out of view and cannot be seen by the angle of the cam. 
Dilara as example
Auriel & Piter also
20 posts were merged into an existing topic: Gossip and off topic posts
What if the realm really doesn’t have a toilet? Then where would they go to do their business? It would be 2 mysteries in one. 
We know going out the window isn’t an option. 
Something is going on in that secret room. You can see Henry go into the room and later the girl (do not know her name). Later all 4 came out of the room (Mira, Henry and the two guest.
Excuse me for contributing. 
I would say that this door in Bella’s place leads to an outside area, in my experience a raised threshold is there to stop rain/water ingress, and the roller blind to keep out daylight/ vision into this area.
The other door appears to have daylight coming in through it too, but as this door is not wholly visible, it’s not possible to see if this has the same raised threshold and roller blind.
Maybe, but also in this region of eastern and central Europe a raised threshold can be seen in many laundry rooms where they have a totally sealed floor in case of a leak.
I remember once the hose came off the washing machine in our laundry room and it was like a b___dy swimming pool in there. 
The only one who can solve these mystery rooms are @Bella_Leo
I quite agree this could be a wet room of some description, but as there is a roller blind, I was erring on the outside area, as I see no reason for a blind on a laundry / wet room. Also, I’m sure there was daylight showing through this door.
Ah, good spot
We can maybe ask Torey he knows everything 
Only joking Torey
I think you are on to something here
I would say, looking at the shape of her apartment, it could well be the penthouse area of her building, you tend to find that these can be oddly shaped due to the architectural design of the building, and this would have outside areas. But as you say, only @Bella_Leo can answer this.