Mei takes off her eye patch to reveal a green doll’s eye. She then tells him of the story from 26 years ago, with the additional detail that in the class picture after graduation, the dead Misaki was in the picture. Later, Kouichi asks Yukari about Misaki, and she chides him to never say that name in Class 3. He then asks his aunt about it and what class his mother was in. She blows him off, but does say that his mother was in class 3. The next day, on his way to meet Mei on the roof, Teshigawara calls him and tells him not to mess with things “that don’t exist.” That night, the nurse calls back to tell Kouichi that the girl who died was named Fujioka Misaki. The next day, he asks Mei about this, who says that she was her cousin. He then asks why no one acts like she’s there, and she says she doesn’t exist. Yukari then rushes out of a class, sees, Kouichi and turns around, then trips down the stairs and impales her neck with her umbrella, killing her.
So we have our first on-screen death, with Yukari getting offed in a rather gruesome and painful way, as she didn’t die for several sections after getting her umbrella shoved through her neck. I suppose technically she’s the 2nd death, as Fujioka could be considered the first, though it was off screen.
I’m guessing the “other part” of the story is basically that after the dead Misaki “graduated” – that exactly things like this have been happening: a disproportionate number of students from class 3 have found ways to get killed, which of course is getting blamed on the death from 26 years prior.
In any case, we found out that Mei wasn’t the Misaki that died in some way, so that clears that up. I’m also swinging back toward the line of thought that this is a series where things merely appear to be supernatural, but aren’t. Of course, that means that Mei’s comment that “no one else can see her” is merely a metaphor and not actually literal. Perhaps it’s because she shares a last name with the dead girl, and they ignore her for that, or because she seems creepy, or some combination.
Maybe it’s some attempt to “undo” the work of the class 26 years ago. Instead of pretending that the dead Misaki was still alive, this class is pretending that the real life Mei Misaki doesn’t exist. I think this is bolstered by the fact that I think Yukari was responding, not to seeing Kouichi, but from seeing Mei in the hallway. This plus the fact that Kazami seemed to see Mei on the roof, and that the class seems aware of her existence I think leds credence to the idea that Mei does, in fact, exist, but the class’s ignoring of her is so extreme that they have convinced themselves that she does not exist.