Money is the currency Urotsuki can collect in her dreams, represented by the kanji 夢 (Yume, Dream).
Obtaining Money
Once per dream, the piggy bank in the dream version of Urotsuki's Room will give you money equal to the percentage of maps you've visited when smashed.
Killing NPCs can sometimes yield 100夢 (1/8 chance). The NPCs in Ecstasy World drop money slightly more often than most NPCs (3/8 chance if chainsawed, will always drop money if killed with the Lantern). The NPCs in Fairy Tale Woods also drop money slightly more often than most NPCs.
Killing Seishonen in Urotsuki's Dream Apartments always yields 50夢.
The Mysterious Maid will give you 500夢 when you interact with her for the first time.
There is a smiling green blob in Graveyard World near the sculpture room that has a 1/3 chance to give you 5,000夢 if you can chainsaw it. However, doing so is very difficult, as it moves around very quickly if the Chainsaw effect is equipped.
If your money is below 500夢, you can find 100夢 by checking the Box Shop Keeper's drawers in Japan Town and going into the gap in the hedges near the Underground Bar.
Once per game, Urotsuki can receive money from a customer in the hotel.
There is a chance that you can find 100夢 at the left side of the drawer in Tatami Room.
In the heart of the Chaotic Buildings, there is a big green creature that has a random chance of giving 150夢 when you chainsaw it.
NPCs in Pudding World have a chance to drop 200夢 when killed.
There is a man in the Oriental Pub who can be found sitting near a noodle shop, who nets you 500夢 when chainsawed. This drop can be easily reset by entering the area again.
After drawing the house in Shape World, there is a 1/6 chance (determined on entry) that an outline of a gnome will be inside the house. Interacting with it with the Child effect equipped will give Urotsuki 1,000夢. Repeatedly entering and leaving the house will 'reset' this event, making it an excellent way to obtain money quickly.
Solving the Shadowy Caves puzzle for the first time will net Urotsuki a whopping 100,000夢. Resolving the puzzle on future visits in future dream sessions will reward money based on the current Map Completion Rate. (100夢 for every 1%).
The black lotus in Lotus Park has a 1/2048 chance of giving you 511,000夢, the most amount of money you can get at once currently.
Spending Money
There are currently only a handful of things Urotsuki can spend money on. The many vending machines found throughout the dream world are the easiest to access. Urotsuki may purchase drinks and snacks from them for 100夢.
Urotsuki can also buy alcoholic drinks (200夢 per drink) at the Underground Bar in Japan Town. Drinking too much may lead to interesting results.
Masks can be purchased from the shopkeeper in the Mask Shop for 500夢 each. These get cheaper by 10夢 with each purchase, to a minimum cost of 100夢 per mask.
Urotsuki can also lose money. The vending machine in Mushroom World, for example, will steal your money and not give you a drink. A sane clown (nicknamed Pennywise) in the gray building of Guts World will also steal some money from you if you try to kill them.
At the very end of the game, money can also be gambled in the Developer Room's slots.