The Hand Fields is a scrolling world filled with many hands in different poses, embedded within the ground. Strange robots and bloodied pillars litter the area, and one can find the house of a bright- haired twintails girl northwest of the entrance from the Intestines Maze.
Directly north-west of the entrance from the Intestines Maze you will find an open hand, which upon interaction will bring you to Fountain World. This is specifically the one directly northwest of the monitor, and only the one closest to the monitor. Any other open hand will simply do nothing to Urotsuki.
The NPCs here include strange, floating, armless robots with bright red, asymmetrical eyes, as well as several stationary, bloodied pillars and a couple of unique NPCs. Most of these NPCs will only make a faint noise upon being interacted with, but they have rather interesting reactions to the Chainsaw effect; The robots, although they die normally, let out a much different scream than normal, higher pitched and slightly less human than normal. The pillar NPCs, however, although they bleed, are immortal.
One NPC, an identical copy of which also appears in Vase World, is a strange brain-like thing with a pair of blue eyes poking through a hole in the front. Equipping the Wolf or Chainsaw effects, much like in Vase World, causes this NPC to grow eyes of pure madness and a menacing arsenal of teeth; despite this, the monster will also flee while doing this, instead of attacking as seems obvious. Interacting with this brain monster with the Bat effect equipped will transport you to the corresponding brain monster in Vase World.
There isn't much to do in this area besides go on a robot genocide, at least until you find the aforementioned house. The golden-haired, split twintails NPC lives inside, and her house is guarded by a strange floating totem bearing a staff. (Who, by the way, reacts to highly dangerous power tools in the exact same way as the pillars do.)
Twintail-chan reacts to exactly five effects; The Telephone and Chainsaw effects will cause her to run away from Urotsuki while the Twintails will (unsurprisingly) make her follow Urotsuki at the same speed. With the Marginal effect equipped, her eyes become crosses, she will grow arms in her back and start walking backward. Perhaps most interesting is her response to the Invisible effect; if you disappear, so will she. (in fact, she's even better at hiding than you are; Turning Urotsuki invisible will leave her shoes in place, but Twintail-chan can make even her shoes vanish)