Two new transfer students will join Class-EIf you look at the seating chart, there are three empty seats; the one next to Ritsu is occupied to Itona. And if you look closely, each vertical row are occupied by students with the same gender. That means the new transfer students would be girls. This would also balance the number of boys and girls, and everyone could shipped together.
"The God of Death" is the Chairman AsanoWhen Lovro tells Nagisa about the "The God of Death", we see the chairman observing Class-E via monitors with a hidden face.
"The God of Death" is the mysterious Yukimura-senseiYukimura-sensei stopped teaching Class-E and disappeared the month the story started to focus more on his part-time job as the assassination world's most feared and ruthless hitman.
Kaede Kayano has a hidden special skillEach student in this class has a speciality, but Kayano, the girl we see the most, has not really done anything yet and she's pretty much The Load. Like Nagisa, she must have a special skill that has to be shown yet.
Alternatively, Kaede Kayano is important to the plotMaybe her skills are average to the other students, but she is important plot-wise.
Itona will have a Heel-Face TurnKoro-sensei frequently offers him to stay in the class.
Gastro, Smog and Grip will come backIt's implied that they will show up in the future.
Koro-sensei doesn't have a choiceHe would destroy the world within one year, but it is not due to his own will. He is also probably have a case of I Cannot Self-Terminate. So he gives the students chance to kill him to prevent the destruction of the world. Also, he has to be killed in a certain way to be really dead.
Nagisa is also a being similar to Koro-sensei and ItonaTentacles seem to start with the hair and Nagisa does seem to have unusually lively twintails that correspond to his mood.
Koro-sensei didn't actually destroy the moonAnd he wouldn't destroy the Earth either. The true culprit is another being similar to him, something he cannot defeat. He hopes that by being defeated and killed by humans, they will get enough power and experience to kill the true Big Bad.
Koro-sensei takes credit for the destruction of the moon to further his own goalWorking off the above, Koro-sensei takes credit for the destruction of the moon because whatever conflict he had with the real antagonist that ruined the moon ended with a threat to attack the Earth in one year. Claiming the destruction and threatas his doing openly would allow him to make whatever demands he wanted of the governments of the world, and so uses the chance to create a group of skilled assassins that would unquestionably be able to kill Koro-sensei, in a bid to tip the odds in his favour during the rematch in March. The entire ordeal of teaching Class E may just be Koro-sensei's attempt to set the most elaborate trap to kill the real enemy by manipulating the resources of worldly government resources he'd otherwise not have access to.
There will be Itona and Ritsu ship teaseNow that we know Itona's backstory, pretty please?
Nagisa's parents are divorcedThis theory is gaining popularity on Japanese message boards, so it bears discussing. Proponents suggest that Nagisa was sent into class E because of the social stigma associated with his parents getting divorced.
Gakushuu Asano will not realize what exactly is going on in Class 3-E, until years after Koro-sensei has been killed.Years after they graduate, Gakushuu will need a hitman, possibly to even kill his own father to take over the school. And after thoroughly looking into available high quality hitmen, he will come across Nagisa's name, and soon many other from the class 3E as well. It's only then that he will realize just exactly what kind of special training were they getting there.
Nagisa takes after his mother...including in his talents for assassination.Nagisa's dad seems like a pretty nice guy, and Nagisa mentions that his mother is the difficult one. Since Nagisa's dad seems pretty milquetoast, it's very likely that Nagisa takes after his mother. If his parents have been separated for an extended period of time, it's very likely that he could have become the way he is from her. Alternatively...
Nagisa takes after his father, who is The God of Death.It makes sense. They look alike, and Nagisa's father lives away from the rest of the family. Nagisa could easily inherit his old man's skills, or even be TAUGHT by him (though that is implausible). The one thing that rules this out is the seeming quickness The God of Death finds Lovro, but it's never specified how much time passed between the two scenes.
Nagisa takes after his STEP-father, who is The God of Death.Following the WMG above about his parents divorced and his mother later marrying someone else. It was his step father who was the god of death.
Koro-sensei Was Once a ManAll the origins seem to show that Koro-Sensei was born in a vat, and he appears human-like in some flashbacks. What if he was subjected to the same experiment on Itona? He could be a Super Prototype, if that's the case.
The woman from Koro-sensei's past is the Chairman's wife!I actually read this in the comments page of some manga reading site so apologies for stealing this. But I thought hey, mangas always pull something like this so why not. She wanted someone to stop her husband's evil educational tyranny (and her son was already turning into a clone of Daddy) so she decided to send an alien in to teach the bunch of kids her husband terms "rejects". Might also explain why the Chairman knows something about Koro-sensei's past.
The woman from Koro-sensei's past was Class 3-E's previous teacher.She was a kind teacher who suddenly vanished because she was killed off in the incident that turned Koro-sensei into a supercreature (if you believe that WMG), and her Last Request was for Koro-sensei to teach Class 3-E in her place. She usually appears in brief flashbacks right before Koro-sensei declares his concern for his students, and in each of them she obviously meant a lot to Koro-sensei. It would really justify why he's so protective of his students and motivated in helping the kids excel: Being their teacher, and thus keeping the promise he made to someone who was very precious to him, is more important to him than the end of the world.
Rather than becoming hitmen, Class E joins the military's special forces. Or opens their own mercenary business.Their skillset isn't limited to being assassins and they already have a link to the military through Karasuma and the others. They also tend to work best as a whole Badass Crew while being hitmen seems more like a solo affair.
Nagisa's mother is Aya Asia, and his father is really Neuro.It would tie into the author's previous series, and explain a lot about how Nagisa thinks. Also, Aya would likely not be a very good mother, what with the life in prison and the "I can't love anyone" thing, so it makes sense.
Asano will have an Enemy Mine with Class E against Chairman AsanoAsano is not only an Antagonistic Offspring, he is visually disgusted of Chairman Asano. Apparently, Asano does not want to become exactly like him and he will not take Chairman Asano's lessing about losing, but he will team up with the very opponents who defeated him in the exam bet and in boutaoshi.
Nagisa is actually Quetzalcoatl, the Mayan Feathered Serpent.Hear me out: The snake imagery, the the potential for death, the feathery hair (including the winglike tufts), and the implication that Nagisa is the best chance of succeeding in the assassination leads me to believe that Nagisa is far less human then is shown. Even if he isn't literally Quetzalcoatl, he might be its incarnation.
The moon is not really blown up.The moon controls the tides, and since there's no news of apocalyptic storms, Korosensei probably did not blow up the moon like we think he did. Knowing his policy for improvement, he might have even altered the tides to be better for the planet.
Koro-sensei destroyed the moon, but not by blowing it up.Nevermind that they explicitly say that the moon exploded; that was the best logical explanation they could come up with for the sudden disappearance of 70% of its volume. Koro-sensei actually converted all of that moon mass into energy (via some method of E = mc^2 ) and stored it inside his body. It forms the crystallized energy of his Ultimate Defense and provides more than enough energy to keep him healthy unlike Itona, whose tentacles require three nuclear power plant's worth of energy to function properly for a month.
Koro-sensei blew up the moon, and its fragments became his kryptonite.The moon's fallout became the basis for the anti-sensei material used in their knives and bullets, and the strange beam of light that Shiro uses to stiffen Koro-sensei's cells is synthetic moonlight that utilizes the same anti-sensei technology.
Kataoka's hairclip will become a Chekov's Gun.The anti-sensei hairclip she made specifically for underwater assassinations was never utilized during her arc.
During the final days before the Earth's destruction, the government will nuke Kunugigaoka in a desperate, last-ditch attempt to save the world.One of the world leaders made the suggestion, which was quickly dismissed not because it would endanger innocent lives but because they figure Koro-sensei would just outrun the explosion. What better way to keep Koro-sensei in range of the nuke than a bunch of civilians in harm's way?
The 'God of Death' is tied to the same tentacle-cells as Koro-sensei and ItonaThe 'invisible scythe' of his could be a similar tentacle, hidden entirely when not in use. Whether or not he had it before or after Koro-sensei's appearance is unknown, but God of Death could either be a wayward prototype that used his potential for assassination or Shiro's newest implant, which would explain his sudden return to the scene after being inactive. In either case, he's apparently directly targeting known assassins that have so far failed to kill Koro-sensei.
Koro sensei ate a Devil FruitProbably alien alien fruit, which turned him into octupus and gives him super speed, but render him unable to swim.