WP #57, #132
The Power Plant (ボール工場, Bōru Kōjō, Ball Factory) is an area deep within the Dream World, accessible from the moving balls in Sign World.
The world has a scrolling background of grey pipes (leading to its latter name) with teal tiles and grey walls. There are also a lot of ":D" emoticons on the walls.
If you enter the world from Elvis Masada's Place, you will be in the restricted area as shown in the gallery below, unless you use the Fairy or the Spacesuit effect to fly over the small gap.
You can enter the main part of the Power Plant in Sign World by going through the middle of the round cluster of white eyed signs. Yellow balls with different colored dots will be rolling around. Interacting with the ball with the red eye on it will transport you to the main entrance of the Power Plant.
The place where you enter has a window showing some of the moving balls you just touched. If you continue to go right, you will come to a pathway where there are a number of tanks containing different monsters. As you go down this pathway, it will get gradually darker, and you will then end up at some sort of cross roads. Step in the middle of the red circle and Urotsuki will fall down a hole into one of the tanks; interacting with the glass will let her break out of it.
If you take the small path upwards that appears before the monster tank path, you'll eventually reach a short trail of White Fern World design that leads to the section of White Fern World that appears right before the area where the Tissue effect is located.