Madotsuki meets many characters in her dreams, ranging from "ordinary" humans and animals to bizarre monstrous creatures. Regardless their appearance, none mean harm if one does neither.
The strange behaviour and expressions of the characters in Yume Nikki seem to exhibit certain personality traits. They influence a lot of the atmosphere of the game, even if they don't actually do much at all.
Many characters play a particular role in the game. Some give Madotsuki effects when she interacts with them whereas others may teleport her to different places. Others may ignore Madotsuki completely and simply loiter in the world of her dreams.
Note: Only Madotsuki, Monoe, Monoko and Medamaude have official names. All other dream characters were named by the fan community. (See talk page).
A faceless ghost found in The Sewers. Gives the Nopperabo Effect when interacted with. Resembles Youmu's phantom half and the PC-98 Bakebake (only minus the face and head piece) from the Touhou Project.
A closet found on the floating island in the Checkered Tile Path with what seems to be a sleeping Madotsuki inside. It can only be seen by using the Severed Head or Midget effects, as all other effects are too big to see inside the closet properly.
A character found sitting on a chair in a room in The Mall, where the Toriningen that changes the window color scheme can be found. He will occasionally sneeze and will turn angry when the Cat effect is used in the room.
Stabbing the eye box in the White Desert with the Knife effect has a 1 in 30 chance of leading you into a dark area where a crowd of these cats can be seen. They are white and have large eyes for a head.
The goblin-esque creatures that are found in the courtyard room of the FC Basement after walking up a large flight of stairs. There are four small ones and one large one that takes five stabs with the Knife effect to kill. The large one has a 50% chance of dropping 200 Yen instead of the usual 12.5% chance of dropping 100.
A girl with hat and scarf found in the Block World. At first, she is invisible (only her hat and scarf can be seen floating in the air), but she becomes visible when the Stoplight effect is used. When interacted with, she will teleport you to different parts of the Block World.
Three humanoid NPCs that can be found on the Sky Garden Edge, watching the UFOs. When moved with the Cat or Knife effect and then stopped, they will return to the edge of the cliff and continue to watch the UFOs. Their names are derived from Jaime Maussan, a famous ufologist.
Long-haired girls with pale purple-tinted skin that can be found at the shore at Witch's Island. There are four of them in this area, simply standing around, not moving. When the Cat effect is used near them though, their appearance briefly changes in a fairly disturbing manner.
A strange creature that lives in the Hot Spring House in the Wilderness, sucking up hot spring water in the dark through a tube out of its head. When stabbed with the Knife, it screams and bleeds, but doesn't vanish. Instead, it changes color and stops sucking up water through the tube in its head.
Six types of NPCs encountered in The Mall - a young boy, a young girl, a man, a woman, a middle aged man, and a middle aged woman. When interacted with, they make odd electronic rattling noises and begin to deform as they walk.
A small pillar-like character with red eyes and spindly limbs, found in a room in the Mall. It has a small cavity on its head from which red liquid trickles out. When interacted with, he will spill an endless stream of the liquid onto the floor.
These are unusually large characters that do not roam around like the NPCs. Most are made up of background graphics and have limited or no responses to Madotsuki's effects. Listed in alphabetical order.
A group of characters seen in Footprint Passage 2 in the Eyeball World. They sit motionless with a dazed look on their face, until Madotsuki touches a nearby button, which causes them to cough up blood with a loud noise.
Large, cyclopean creatures with mouths in their stomachs, these things are found mainly in The Footprint Path. There is another one in Hell who has a 1 in 256 chance of teleporting Madotsuki to the Footprint Path when stabbed with the Knife.
Strange, flickering objects seen a number of times in the game. They can be witnessed in the skies of the Sky Garden Edge, on the Martian Summit or occasionally in the background of the Staircase to the Sky in the Wilderness.