If all you have is a hammer...
WP #24, #42
Nail World (釘ロボ, Kugi Robo, Nail Robot) is an area filled with nails sticking out of the ground, accessible from the Warehouse by interacting with the three bloody nails.
Nail world is a large scrolling world, with the most prominent features being nails sticking out of the plain white ground.
A large mannequin with Urotsuki's plaid pattern cut into its chest can be found lying somewhere in the area, which bleeds if you chainsaw it. If you chainsaw it five times, it will transport you to an area sectioned off from the rest of the world. Here you will find a lady in a white dress spinning around on a platform. If you interact with her, her head will come off and she will spin around even faster. An image of her will flash onto the screen and more headless women will appear on the other platforms and spin around as she did.
A black dog-like creature with a big green mouth and green eyes can also be found here, wandering about the area.
Red Nail PassageEdit
Going through the hexagonal-shaped doorway to the southeast takes you to the Red Nail Passage. This area is much darker and features a red scrolling background. If you stop by one of the red blocks with holes in them and interact, a tribal image will flash up on the screen (like the pictures in the Sewers in Yume Nikki).
Following the path to the end will lead you to the Window Room. You can also pass through the Window Room to get outside the restrictions of the path, or go through an inconspicuous hole in one of the rows of nails. Outside the path you can find three bloody nails in the ground that transport you to the outside of the Warehouse.
Another inconspicuous hole in the rows of nails can be found roughly halfway down the path, which leads to a small section of the path containing a piece of paper stained with black ink that has been nailed to the ground, which will take you to Pencil World when interacted with.