The Debug Room is an entirely black room that can only be accessed by opening Yume Nikki with RPG maker 2003 or changing its map name (Map0001.lmu) to another map, like Madotsuki's Room awake (Map0003.lmu). It contains a few objects that were probably used for game testing:
- The Mirror gives you the Fat effect. The mirror was used in older versions of Yume Nikki for obtaining this effect, and was located in Hell. Garbage text may display if playing the English version due to the string being untranslated. Under normal circumstances, it should show up as "★ふとる★".
- The Neon Creature plays a sound effect and stops the music, if any is playing. It acts like a typical NPC in game, reacting as you would expect from the Cat, Knife, and Stoplight effects.
- The FC World equivalent to Witch Madotsuki plays the 8-bit version of the effect sound.
- Nekoin (the cat coin) 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 you can't move.
- 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. Waking up is possible if you were already in the dream world prior to entering the Debug Room.