A fairly average guy, except that he has the power to see into people's dreams. His encounter with the mysterious Merry Nightmare changes that, and he vows to be her companion, and to help her find her way back to the world of dreams. It's hinted that he and Merry have met somewhere before, and because of his abilities and potential, Chaser John Doe speculates that he may be Not Quite Human.
Heroic BSOD: He gets hit with this after he finds out that Pharos' host is his best friend right as Pharos takes over Takateru's mind and body completely. And the only reason Pharos had enough time to do that was because Yumeji promised Takateru that he wouldn't use his 'dream vision' since it made Takateru uncomfortable.
Merry Nightmare is a Dream Demon that has severe amnesia. She knows who and what she is (she's a Dream Demon, and for some reason a very powerful one), but she doesn't know how she got from the dreamworld to our world, or why she's stuck here. She is unlike others because she has her own manifestation in the human world. Her only hope of finding a way home is to hunt down other Dream Demons in our world, and to find them she needs Yumeji's help. Yumeji has labeled her with the title "Yumekui Merry," or Dream Eater Merry.
Stripperiffic: Indeed. Her attire includes clothes such as a top which leaves most of her stomach exposed, a short skirt that displays her legs rather nicely, and of course there is the obligatory thigh-high stockings.
Super Toughness: Dream Demons can be hurt, but they — especially Merry — can take a lot more punishment than ordinary humans. For example, there's a scene in the manga, where Merry, Yumeji, and a few others have stumbled into Maze's dreamspace, that involves Yumeji about to be hit by a robotic clown wielding a giant sledgehammer; Merry leaps in, takes the hit for him, and proceeds to beat the robot into scrap while shouting "THAT...HURT!!"
Isana is a childhood friend of Yumeji's, a fellow member of the Writing Club, and harbors strong feelings for him. She lives with her father and works at the family-owned Maid Cafe. She quickly befriends Merry, and it is hinted that she and Yumeji met her at some point in their childhood.
Tropes associated with Isana:
Adaptation Dye-Job: In the manga, her hair is purple-tinted, but the anime turns it white.
Hollywood Pudgy: Invoked. She's very insecure about her weight, and occasionally teased about that insecurity, but she still looks cute and petite to the audience and none of the other characters seem to actually care.
Chapter 39 takes this to another level.
Idiot Hair: Like Yumeji, she's not particularly stupid, just not a genius.
Another member of the Writing Club, reflected in his odd habit of composing haiku at random moments, often with completely mundane subjects. As the only other male member of the club, he is shown to be good friends with Yumeji, and there seems to be a budding romance between him and Saki. He's also the unwitting host to the Big Bad Pharos.
Expository Hairstyle Change: When Pharos takes over his body he flips his hair back Aizen-style. After that incident is resolved, Takateru flips his hair back while bragging and causes Saki to panic, thinking he's turned evil again.
A close friend of Yumeji and Isana and a fellow member of the Writing Club, she seems to be fascinated by Yumeji's ability to see into dreams. She is quite confident and outgoing most of the time, but notably becomes rather timid when she's alone with Takateru, who she is hinted to like.
President of the Writing Club, and unwitting host to Chris Evergreen, one of the first Dream Demons that Yumeji and Merry encounter. Chris appears to her as a pen-pal who she only knows through text messaging. She dreams of becoming a novelist.
Most Writers Are Writers: Her dream is to become a novelist. This is actually becomes an important plot point: the fact that she kept that dream even after Chris was removed from her proves that Dream Demons can in fact be sent back to the Dream World rather than being killed.
Yui is the vessel of the Dream Demon, Engi Threepiece, but unlike possessed persons seen thus far, her relationship with her Dream Demon is a sisterly one of mutual respect. Yumeji and Merry first meet Yui at the supermarket, and soon discover that there is more to her than meets the eye (unless it's Yumeji's eye). There are several jabs at her inability to cook, for which she has been labeled "Magical Chemical Cooking" for her foods' severely distinctive and lethal tastes.
The first benevolent Dream Demon Yumeji and Merry meet. She is blinded by revenge towards Hercules, the Dream Demon that brought her older sister Patty there and ended up killing her. For this reason, she came to the real world, where she met Yui Kounagi. She is currently inhabiting Yui's consciousness, with her permission. She wields (several) swords and eventually befriends Yumeji and the like.
Tropes associated with Engi:
Action Girl: And how! She's one of the toughest fighters around.
The Big Girl: Definitely a powerful fighter, although she's not as good as Merry.
Hunter Of Her Own Kind: Unlike Merry, she has no way to send Dream Demons back to the dream world, and she has learned to kill Heracles' underlings in cold blood, although she tries to avoid this now that Merry is around.
Lady of War: Is very kind and polite to anyone she's not trying to kill.
Prehensile Hair: Not just shaped like wings, it can actually be used as wings!
Revenge Before Reason: After the battle with the twins, she's pretty much hellbent on killing Heracles even if it means her vessel's life and having to fight her friends. She gets better after Yui calls her out about it.
Rapunzel Hair: Her hair is very long and shaped into a pair of wings.
A mysterious cat-like Dream Demon that first appears to Yumeji through a recurring dream, having taken an interest in Yumeji and his ability. He is very powerful and owns an impressive army of other cats, which manifest into female kemonomimi during battles. His intentions and loyalties remain unclear, and he refers to himself as an "ally of truth", but he has nonetheless become something of a mentor figure to Yumeji. He currently inhabits the body of a black cat in the real world.
Tropes associated with John:
Aloof Ally: Only helps when he deems it necessary.
Meaningful Name: Like all Dream Demons. He is a nightmare of pursuit ("Chaser"), of being stalked and hunted by a faceless menace ("John Doe") for an unknown reason, across a cityscape that feels familiar but subtly shifts and changes so you're never quite escaping no matter how hard or long you run. It's also meaningful that he is one who hunts after the truth, as a "John Doe" is a pressing question of identity, a mystery needing an answer. He's compelled by his nature to embody his name in many possible ways.
The main antagonist and a very powerful Dream Demon. Very little is known about him, except that he is rallying fellow Dream Demons with the apparent intention of occupying the human world and supplanting the human population. John Doe speculates that this is probably not the full extent of his plan. His human host is Takateru, a close friend of Yumeji's.
Jerkass / Kick the Dog: Yeah, not like it wasn't completely obvious from the start, but after he takes over Takateru completely, he rubs Yumeji's face in the fact that, by keeping his promise not to use his "dream vision" on Takateru, Yumeji essentially let Pharos completely take over his host. Then he taunts Engi about how weak her sister was, stating that his fight with her was boring to the extreme.
Meaningful Name: Pharos is the name of several historical lighthouses, including the great lighthouse of Alexandria. He's a dream of guidance, signaling others in their travels. But he's also a dream of flame (as lighthouses had to be lit by fire) and is a consuming destroyer who wishes to burn brighter. "Hercules" is the most obvious part of his name - he is a nearly godlike warrior, impossibly strong and dangerous to have as a foe. And also, as the original Hercules served others in his trials and only became a demigod, so is Pharos not the true greatest power and instead turned out to be the Dragon rather than the true villain.
Visionary Villain: Although he's carefully avoided telling his underlings his true purpose, this guy has a clear idea of what he wants to achieve and how he'll go about it. Said goal is to alter the conscious world so that Dream Demons can exist without host bodies.
A notable recurring antagonist, and an underling of Heracles, whom he serves under with pride. While not the biggest direct threat and notably cowardly, his tricks and creations can be quite dangerous on their own. Merry has sent him back to the Dream World.
Tropes associated with Landsborough:
Cyclops: He only has one eye and when in control of his host closes one eye.
Demonic Possession / Grand Theft Me: Unlike some of the more benevolent Dream Demons, he completely took over his host's body without permission. This eventually caused him trouble, since a host personality not given freedom once in awhile is liable to surface at exactly the wrong moments.
Dirty Coward: Once Merry and Enji get past his tricks, he's an easy target and most likely would've kicked his ass long ago. It's only because of his human host that they lay off from destroying him. Too bad for him, Merry found a way around this problem and locked the gate to their human hosts.
Squishy Wizard: By his own admission. Still claims to be tougher than ordinary humans, but Yumeji isn't an ordinary human.
A Dream Demon who faithfully serves Heracles, she operated through the body of a very young girl named Minato, who Yumeji and Merry had previously saved from another Dream Demon. She works alongside Maze Landsborough to take down Yumeji and Merry, but they both end up getting sent back to the Dream World. She is portrayed as sadistic and wears revealing clothing, for which she is usually remembered.
Demonic Possession: Unlike Maze, she seems to have it down to an art, and knows to give control back to the original owner once in awhile.
Improbable Hairstyle: There are several streaks of a light color running down her dark hair. What colors they are exactly is hard to tell since she hasn't appeared in any color pages yet, but it definitely wouldn't be natural on a human. Not that there aren't human characters withoddly colored hair.
Knight of Cerebus: Definitely one of the most serious threats the group has faced yet.