I think it's only accessible during an ending when you're awake.
Noone of the endings let you move as you want when you're awake.
I'm really not sure… this is all it says on the wiki: "There are also two open doorways on this floor, but both lead to the same room, which is lilac-tinted and is filled with stacks of furniture. There is also an intriguing door with Urotsuki's shirt design on it as well as a keyhole. You are only able to enter it during one of the endings when you are awake."
I actually managed to unlock the door once, though I was messing with the debug room so I don't know how I triggered it. After checking out various things in the debug room I returned to Urotsuki's room [awake] and a key dropped from the roof. I took it and it stayed in my inventory as an item. With the key I could actually exit Urotsuki's room while awake and unlock the door.
It leads to a "developer's room" of sorts where you can talk to various people who worked on the game.
I tried to reaccess to the endings by dropping all the effects as usual, but the stairs doesn't appears and pinching the cheeks have no effects. I don't know if it's a bug related to regain and redrop the effects or simply can't reaccess to the endings once get all three.
Well, the debug room on older versions could make you see the endings when in the actual games it wasn't possible. Maybe the key is just partially added and impossible to gain on regular game for now.
Go on the computer, select data then select the second options. All the endings you've unlocked are re-accessible from here.
When I try to play this game (or any other RPG Maker 2k/3 games), my display now flickers like a fucking christmas tree in fullscreen. I have no idea why this has just started happening, but I can't lower graphics accelleration and no other fullscreen applications have this problem.
Nevermind, I fixed it by closing the process that minimizes my headsset property control to the taskbar tray.