The Debug Room is an entirely black room that can only be accessed by opening Yume Nikki with RPG maker 2003 or changing its name map (Map0001.Imu) to another map,for example Madotsuki's Room on Real Life (Map0003.Imu). It contains a few objects that were probably used for game testing:
- The Funhouse Mirror give you the Fat effect, but with garbage text.
- The Neon World creature makes its regular sound effect.
- 8-bit Witch Madotsuki plays the 8-bit version of the effect sound.
- The cat face gives you all of the effects and warps you to White Desert B. If you already have the effects, you will get duplicates.
- Flying 8-bit Witch Madotsuki starts the Witch's Flight event, but there are two Madotsukis, one who is flying in the background, and the player, who starts offscreen.
- The chair in the top right corner lets you save, but you won't be able to get out of the chair. Sometimes, the Witch's Flight event plays at the same time.
- Going directly to the left of the traffic cone warps you to Mars-san, but you are put in a place where you cannot move or wake yourself up.
Note that the mirror was used on older versions of the game instead from the current way to get it.