I did really like it though. Summary: Ichijo Mashiro is the main character, and has an extremely odd secret. From the waist up he is anatomically male; deeper voice, more defined features, big hands, broad shoulders and flat chest. From the waist down he's female, complete with a functioning female reproductive system. Awkward? A bit. Thing get trippy when the school nurse brings him to weekly after school lessons that involve shared dreams with other students. The students in these lessons cannot graduate until they find a key in the lessons to unlock the exit.
The dreams take on the form of one person's memories or view of the world, and the people inside the dreams take the form of their souls; Ichijo changes from fully male to fully female randomly while in the dream, making him easy to recognize in the real world, but many of the other students have warped or hidden forms. Each student has three beads around their neck that break with a shock or trauma; when all three break, they wake up from the dream and miss out on their chance to graduate that week.
Ichijo attempts to do several things over the course of the series. The first is figure out what he wants to live as: male or female. Going off of that, he struggles to discover if he loves a boy or a girl who are both students in the extra class. He also attempts to discover the identities of the others in the class, both to survive the lesson and to help them graduate.
The rest of the post will contain spoilers, so I'll cover it up
In the end of the series it SEEMS like the class is revealed as a dream from Ichijo's mom, who is pregnant with twins in a hospital that catches fire (Ichijo's name is actually a combination of his dad's and mom's). In the final chapter, the remaining four students all leave the dream to find their school on fire - rather than escaping, they stay to pray for Ichigo to graduate. In the real world, it seems like the students were other pregnant women (or maybe their children?) in the hospital ward; and when the students "woke up" from the dream, in reality their real life counterparts asphyxiated.
However, I don't understand what the point of other people's issues was in the dream class if "graduation" is simply being born. With Ichijo it made sense: the class was to decide which twin would live and which would die. But what about the Giraffe? His issue was being a genius but bullied - what difference would that make with an unborn child? Or what about the ones who didn't graduate but instead chose to stay behind? Kureha's issue was being brutally raped when she was 5... what the heck does that translate to in the real world? And does that mean that by choosing to stay behind to watch Ichijo graduate she chose death?
There were also several symbols or themes not really explained. The first one was the black moon. The closest it comes to an explanation was at the end, when it turns out it's a hole on the other side of the graduation. But there is a black crescent moon out most of the time that only some characters can see. Another was the bird cage on the key, which was explained by the author's notes near the end, where "bird in a cage" is the Japanese equivalent to "bun in the oven." Some spiffy foreshadowing, but quite obscure. I'm also not sure what it means when black birds fly out when Ichijo's stomach is cut open. What about the play at the end? That seemed to come out of nowhere, but I feel it must have had some explanation behind it.
The character choices also seemed odd. On the surface, the dream class was supposed to be about figuring out what you want or facing your own shortcomings in order to graduate. In actuality it often came down to "I stabbed you, got the key, and walked out. I'm still a monster!" All those who graduated never seemed to really accept who they were. The admirer never admitted his love. The giraffe used people to get out. The mermaid killed people to escape (and was a completely random arc, by the way). Heck, the only person who really confronted themselves was the quiet girl (Ohara), but she disappeared because she refused to go to the class. It was revealed in the real world that her mother miscarried. Two of the characters at the end just show up in the last couple of volumes, and one doesn't even get a name until the ending.
Huh, talking it through I guess it wasn't all that hard to figure out most of the stuff, except for maybe the symbols. The nurse is also never really explained, or what the high school itself is (purgatory? a repository for newborn souls?).
Anyway, the content is a bit mature, but the story is pretty good and makes you think. If gender-bender stuff turns you off, might want to skip it (although besides kissing, there's not really fan service), but I really enjoyed it. It was creepy, a mindf*ck at times, and had a pretty good surprise ending foreshadowed throughout the entire story.