[DesuX2]

I love Another, it reminds me very much of Higurashi, Umineko and Final Destination. That said, I have a personal theory of what is going on in the show, as of viewing of Episode 4.

Spoiler for Personal Crack Theory from Epi 1-4:

Misaki Mei is real. (i.e she exists in the physical world)
The "curse" existed in the past, but is currently brought to life by an unknown perpetrator for a currently unknown purpose.
Kouichi and Mei are descendants of the original pair in the "curse".

NOTE: I lean very heavily towards the "Misaki Mei exists" theory in part because of the scene where Mei is seen in a mirror. It seems unlikely that in a horror show that something as cliched as "ghosts can't be seen in a mirror" would be omitted when the writer was making the draft.

NOTE2: I refer to "curse" as the incident that occurred 26 years ago. The entire thing, whatever it is.

Like the others who have proposed the theory that Mei exists, but everyone is ignoring her. I think that theory is sound, except for the part where she is a ghost/manifestation of the curse. First of all, people can see Mei. They just pretend not to. Note the reactions of Kouichi's classmates whenever he tries to run off to the rooftops or to see Mei. It is always a pained/startled reaction. Refer to Epi 2, where from a third person'a point of view, Mei is clearly in view. Not so much because they think Kouichi is befriending a ghost, but because he was trying to associate with someone associated with bad luck.

The only evidence for this is that Mei's name contains the name "Misaki". It is the same name of the student that died 26 years ago. As such, students of Class 3 shun her because her very existence in the class is an ominous sign of the "curse" returning. This explains Mei's comment about how she "doesn't exist", because metaphorically speaking, in the eyes of Class 3, she is nothing but a living wraith, and to deny her existence would be in the best interests of everybody. Both Mei and the rest of Class 3 are preventing a repeat of the same circumstances that formed the "curse" 26 years ago.

I got this idea from Epi 1 where someone said that Class 3 "associates your (Kouichi) name with death".

It is entirely possible that his family, who have been proven to attend YK School for three generations (Mother, Aunt, Kouichi), is innately connected with the "curse". I theorize that the Sakakibara family, being outsiders, have a bad tendency to break from the conformist nature of the town, and ask "why". This is in reference to Kouichi's conversation with his aunt where she rages at how the parrot keeps asking "why", and her advice that the "group" is more important than the "individual" in this town.

Building on this theory, I kind of get the feeling that there is some deep connection between Mei and Kouichi. After their first meeting at the dollhouse, there is a short scene with two friends talking about how both of them are "stuck" with each other. Using the same language that Mei uses nonetheless. If I were to take that conversation metaphorically, it seems to refer to Mei and Kouichi's relationship, where Kouichi does not know anything about Mei, but Mei seems to know everything about him. I theorize that this connection is that the boy who declared that "Misaki exists" 26 years ago is in fact someone from the "Sakakibara" family. This explains why people are afraid of Kouichi, and keep questioning him about his birth. Mei knows this, and in order to distance herself from the "curse", and Kouichi being socially isolated like she is, she tries to distance herself from him.

Of course, there's a gigantic monkey wrench in my theory because of the entire "doll" motif. I think I'm thinking too two-dimensionally about this, because if Mei is really a spirit, then why bother with the doll motif? And how does one explain the stiffness of Kouichi's classmates both when they visit him, and when he introduces himself to his class. There is a gigantic difference in style if you rewatch the first two times that they are presented. Their limbs are stiff and unnatural, as if they were dolls. Then there's the creepy old lady who owns the doll shop, who repeats the exact same lines twice when Kouichi visits her shop, again, the doll motif. Not one bit of human nature in them. Could it be possible that the entire town is dead, and are just dolls? Then who is controlling them? I don't get the connection between the supernatural and the doll motif at this point, so I have no idea.

Very soon, people will die mysteriously. Unseen by anyone of course. This is an established fact of horror shows. I contend that the first cute girl's death was merely a coincidence. Someone will start prepertrating murders for an unknown purpose, and try to pin the blame on Kouichi. Why anyone would do this, I don't know. The closest to a suspect I can find is the black haired guy who likes the tsundere red-haired girl. Maybe he's killing people because he doesn't want her to go to Tokyo, and is jealous that Kouichi will be in close proximity to her? I don't know, it's probably a minor detail that I am exaggerating here.

Unsolved Mysteries

What happened 26 years ago?
What happened 15 years ago when Kouichi's aunt was at the school?
Does Mei really exist?
What is Mei and Kouichi's true connection to the incident 26 years ago?
What purpose does the "countermeasure" division serve?
What is the use of the "doll" motif in the show?