This may be eventually made obvious; but hey, I'm only assuming from watching episode 3 of the anime.
- Jossed. The manga is being translated by several scanlation groups. It's rather deep into the story, and there it's been revealed that Mei isn't invisible at all. Everyone chooses to ignore her and treat her as if she weren't there. This may seem cruel, but the reason for this is very understandable: ever since the incident with the original Misaki in nineteen-eighty-whatever, an "extra" student mysteriously appears in class 3. This student is dead, and everyone's memories is automatically altered so that they can't tell who it is. But everyone still knows that this dead person is hidden amongst them, but no one will be able to tell who it is until graduation, when their memories revert to normal. The presence of the "extra person" causes an imbalance that leads to the inexplicable deaths of anyone connected to class 3 or the previous class 3s. The only way to counteract this is to treat one random student as if he or she didn't exist, thus neutralizing the imbalance.
- Alternately with the info in the first theory on the page when she realised that Kouichi wasn't ignoring Mei she realised that the "curse" might be active for that year (the previous year hadn't been affected, the curse can affect family members of students if they also were in the 3-3 class) and caused her Mother's accident, she then suffered a Freak Out and slipped due to being overcome by her own panic and not paying attention to where she was going.
- Jossed second victim isn't even featured in ending at all
- Alternate theory: Those that do die won't necessarily be shown in the ED, but if they do appear they will die in the order they're shown.
- If that's true, that makes Kouichi the Dead All Along student, since he appears first but has not yet died on-screen.
- Alternate theory: Those that do die won't necessarily be shown in the ED, but if they do appear they will die in the order they're shown.
- Double-Jossed: The last person shown was the first to die. (The OVA shows that Fujioka Misaki's hair is brown, not pitch-black like Misaki Mei's.)
- Presuming the WMG above this one holds, this is what will happen to the OP and ED to match events in the story.
- It might also be that the bird is repeating Ritsuko, Kouichi's mother's, last words.
- This seems unlikely, given how long ago Ritsuk's death was. Could the bird possibly have been alive then?
- Depending on the breed some birds can live in excess of 25 years.
- Third variation related to the above, it's the words of Kouichi's father when he was mourning Ritsuko.
- Jossed. It's a pet Ritsuko and Reiko's parents bought to help with their mourning of Reiko's death, that's why it says "cheer up!" That's also why it asks "Rei, why?" It's parroting Kouichi's grandpa.
- Possibly Jossed as of Episode 10. According to Matsunaga's confession on the tape, the only way to stop the calamity is to find the extra and "Send it back to death" by killing him/her.
- Confirmed in episode 10.
- Dude, you're totally wrong. Sakuragi was the very first person to "fade into" the picture and look what happened there.
- My mistake then, i'm pretty damn bad with names and faces, carry on WMG.
- The students who visit him question that they know him from somewhere, which is due to knowing that he died a previous year as a victim of the curse. They can't remember this because everyone's memories are altered to accommodate him, as it goes every year. It's even said that the name Sakakibara is associated with death to them, though it's not explained why.
- This seems to be supported by episode 6: Kouichi's father's memories seem to change mid-sentence on something when he's questioned about the past, and his aunt can't remember something important about the year his mother died. Maybe he actually already died in birth?
- Unlikely; if he died at birth, there's no reason he would seem so familiar to his classmates. If he died at all, it was a year and a half ago, as implied by being the apparent time of disputed memories in his father.
- Also seems to be supported by Koichi's dream in episode 7. In the dream, Mei tells Koichi that he's the dead student. If this is true, then it becomes Foreshadowing combined with Dreaming of Things to Come.
- This seems to be supported by episode 6: Kouichi's father's memories seem to change mid-sentence on something when he's questioned about the past, and his aunt can't remember something important about the year his mother died. Maybe he actually already died in birth?
- Jossed by Misaki in episode 10.
- The reason for the weirdness around him and his family is that the Extra is related to him.
- The reason the students say the name Sakakibara is associated with death to them is because there was a Real Life serial killer the year before the story takes place with the same surname. It has nothing to do with Kouichi himself.
- The series seems to make effort to avoid the obvious answers as far as possible, so a double-switch might be a potential solution. She has a credible death-story as well (her eye-tumor at the age of four), and her strange relationship with her mother might be due to the fact that they haven't actually had a mother-child relationship in over a decade.
- It's not been stated (to my knowledge) that the dead student actually died at that age so she could be there and a combination of her being under her maiden name and the curse's alterations of memories and records (i.e. the class photo would be changed) perhaps helped along by people's Weirdness Censor would hide her.
- A consistent feature of the curse is that peoples' memories are altered to include the extra up until the point of either graduation or the premature death of the Extra. This has held true for the current Class 3. One point on this matter that stands out is one occasion where Koichi is speaking to his father, who mentions having been to Yomiyama one year ago, conflicting with Koichi's memory that he'd never been there after his birth. His father backpedals to go along with this right after. There should be no reason to change such a recollection, unless perhaps Koichi had direct contact with the Extra during that time. Who did we see Koichi meeting in flashback in episode 10? Izumi Akazawa.
- Ultimately Jossed all around. She dies from a balcony fall in the light novels, cut down by a shattering window in the anime, survives the manga, and in none of those cases is she the "Extra."
- He just didn't die like Teshigawara thought, and that's why everybody still remembers him.
The Shinigami Realm also suffers from the dead person masquerading as an alive one, so the King tasks one of the Shinigami to kill the Extra; the problem is the Extra's influence on memories alters its own death date thus making the Shinigami eyes useless, so he start randomly killing the students until he gets the right one. Hence why a lot of the deaths are so illogical; it's because the bored Shinigami is playing around with how many ways he can kill a person. Takabayashi didn't die from a natural heart attack, but because his written death was too impossible and so the Death Note simply killed him via its usual method. Once the Extra is dead the Shinigami goes back to his usual job until the next year when another one has to do it.
It will involve a new class trying to stop the curse once and for all. Misaki or Kouichi might make a guest appearance as a teaching assistant or school staff. This first series would essentially be a big prologue to the sequel, which would explain why it's set in 1998 for no apparent reason.
A burakumin girl (the descendants of Japan's Buddhist equivalent to the Hindu "untouchable" class, who still face some discrimination) was a member of Class 3 back in at least 1946 (26 years before the curse's previous appearance). Her family was of course rather poor, and so she wished to be able to pass the entrance exam to Yomiyama North Middle School. The class had only 25 desks (just one short), and so she was forced to stand. On top of all that, postwar Japan suffered severe food shortages, and not only could her parents not afford to make her a lunch, she had no money to buy and her classmates refused to share theirs. Eventually her grief and loneliness at being from "the bottom caste" and literally "the odd girl out" consumed her.
- The "extra" is either a familiar of hers, or perhaps just an entity created whole-cloth from her powers, assuming the form and personality of one of the class members' recently deceased relatives appearing every 26 years, in recognition of the 26 students in the girl's class. And the Higurashi-esque (ahem) Witch Hunt at the end of Episode 11 was just as planned by the Incubators, knowing the scared, suspicious students would likely suspect a quiet girl like Mei, who would also have possibly made a contract.
- It's explicitly stated that the phenomena is not a true 'curse' since it has no malice, and has no guiding intelligence behind it. It just happens.
- Have the school have a class 3-3 on the roster but don't put anyone in it. That way class 3-4 really is 3-4 and not 3-3 under a different name.
- Ways this could go horribly wrong: the Curse/universe might react to having a whole class that doesn't really exist by making a whole class of Extras.
- This was confirmed to be attempted in the series; the curse somehow always knew which class was "supposed" to be 3-3 even if names were different.
- Have the entire school/town gather at the start of each year before the class rosters are made and symbolically "kill" and bury an effigy of the dead student to acknowledge that he's dead. Only put people in class 3-3 that were there.
- Ways this could go horribly wrong: Since this is a horror game, they would probably come up with the idea that they had to use an actual student as the effigy and kill them when they could just use a doll or something.
- Have the entire class of the original 3-3 that started the curse gather and acknowledge that Misaki was Dead All Along.
- Add or subtract at least 5 people to the roster of 3-3 and hope the imbalance confuses the curse enough to stop it from doing anything.
- Add Misaki's name to 3-3's roster every year and then cross it out. So the class has an extra person on the roster who is already acknowledged to be dead and not actually in the class.
- Keep Mei/ people like her on staff so they can immediately identify and eliminate the Extra.
- Burn the entire school down. It's the only way to be sure.
Additionally, the curse they cause is also a misguided attempt to bring themselves back to life. They hope that the person killed will be treated like they were alive just like Misaki was, hence creating another slot for a ghost to impersonate a living person. However, this is just not the case so these deaths just keep happening for no seemingly no reason. This is also why the extra student is never killed in any year, as mentioned by Katsumi since his year is the ONLY year that ended short because he killed the extra. The dead student is a ghost themselves and is not affected by the misfortune.
The Extra is created by Misaki rising from the dead and rejoining his class, taking on the appearance of a deceased student or teacher, and all the deaths are being caused by him, telekinetically. The only reason why the act of treating someone as if they don't exist works sometimes is because the person who is erased from the rest of the class is the Extra, who is Misaki's ghost. Of course, there are moments where Even Evil Has Standards, which might explain why Misaki didn't kill Koichi before he could kill him in his Reiko disguise because he couldn't bear the thought of his own aunt being responsible for his death.