Copy and pasting the text of both of my main two main reddit theory posts since they're too connected to be kept completely separate.
First, what erasure actually is:
There are a few bits in the current arc where Akane mentions that Tsukasa's supposed to be erased. However, the odd thing is that Tsukasa's actions clearly don't seem to be erased as he still went into the pit saving Amane and Amane remembers him. However, the results of those actions were vastly different, Tsukasa never got to grow up in this timeline and Tsukasa lacks pupils in this timeline so clearly something was done. I think it's because Tsukasa was sent to the far shore leading to him appearing to be "erased" in a similar vein to how Aoi appeared to be "erased" when she was sacrificed. It would also explain why some people, like Amane, still remember him.
- Tsukasa isn't trapped in the red house like he should be considering what Kou said in 121: "If you die here, you become a prisoner. Trapped in the belly of the red house." While Tsukasa technically didn't die in the red house in the original timeline, he clearly died at 4 or around that age in this timeline anyways, yet isn't stuck in the red house. Why not? Because he was teleported to the far shore.
- Another piece of evidence I have is the rumor about Tsukasa which back in the 1980s, it is said by one of the students doing the summoning ritual: "This circle is going to act as a gate to the spirit world." This implies Tsukasa has been summoned from the far shore to the near shore.
Nene is going to end up accidentally erasing Amane and this is why:
The big clock and the hourglass have many similarities. Not only are they both time travel devices associated with the clock keepers, they also have similarities in how they curse users. To explain this, Iāll use Amane and OG Kako.
OG Kako: Goes back in time with the hourglass and is unable to prevent the accident that Marieās parents were in. The hourglass curses him by erasing Marie from existence. Meanwhile, the hourglass steals bits from his soul each time he goes back in time.
OG Amane: Goes back in time with the big clock and fails to save his brother since both versions go into the pit. Then his brother gets āerased.ā Meanwhile, since Amane is the most likely choice for the catās identity, it would mean he also lost part of his soul for going back in time.
Thereās a pattern here: someone is sent back in time, fails to make the meaningful changes they want, lose part of their soul, and to top it all off, the person theyāre trying to save gets erased.
Now letās look at Nene:
When Akane is about to send Nene back in time, he emphasizes to her about helping Amane: āIf anyone is going to tamper with honorable no. 7ās past, I canāt think of a better person for the job.ā This is quite odd considering previously Akane had only focused on the change being about Tsukasa. Furthermore, Akane doesnāt stop counting when Nene expresses that sheās not ready yet, like he wants her to fail. Nene later on says sheās going to save Amane in the same chapter Amane says heās going to save Tsukasa, that draws parallels to their situations.
When Nene is actually back in time, she fails to actually change anything. Even after she realizes she needs to stop Amane at the end of 129, she ends up not doing shit in 130 to actually stop him.
Hi! I know itās been a long while since you sent these, so Iām not sure if youāll still see my response, but thank you so much! Iām sorry to answer so lateāfirst the holidays and then a ton of schoolwork was keeping me super busy, so I apologize for such a long delay. This theory made me think a lot about the timeline(s) of everything in TBHK, including time paradoxes and stuff. Anyway, Iāll get started with my own thoughts on the erasure theory:
Firstly, I completely agree with the idea of Tsukasa being in the Far Shore instead of trapped in the Red House. Like you said, the Far Shore is the āspirit worldā the students were talking about. My guess is what happened to Tsukasa was more like death than true erasure (what happened when Kako accidentally prevented Marie from being born in the first place). It all made sense to me until I reread ch. 121 and noticed that Amane says this:
To my understanding, he basically implies that Tsukasa died because Amane sacrificed him to the Entity. But for some reason, even though he would have died in the Red House, Tsukasa isnāt trapped there like the other souls. I still think heās in the Far Shore, but there must be some explanation for why his body isnāt bound to the Red House.
(This is kind of off-track, but if Amane was the one who killed Tsukasa like he says, he wouldāve done it at 4 years old. Tsukasa in this timeline died at 4, and Amane wouldāve been the same age⦠meaning he wouldāve already been possessed by the Entity by that time.)
Then, there's 13-year-old time traveler Amane, who is drawing a kind of parallel to Kako's experience with the hourglass. Like you said, they go back, fail to make the change they want, lose a piece of their soul, and then the person they're trying to save ends up gone. Even if Tsukasa and Marie weren't necessarily erased in the same sense, the pattern still holds up. And Nene has two of those conditions met: she goes back in time, and presumably pays for it with a piece of her soul. From here, she could either reinforce the pattern, or be the one to break it.
As for the possibility of Nene erasing Amane, I think it would be pretty intriguing to see this happen (especially as a parallel of Kako and Marie). The story could definitely take this in an interesting direction: What if the best outcome for everyone is if Amane/Hanako never existed at all? If she erases Amane, itād be pretty safe to assume that she also erases Tsukasa, meaning that his body would never be sacrificed to the Entity, which might solve some problems. But to erase Amane completely, Nene would have to go to a point in time before he was born. Just sending him to the Far Shore after he's already been brought into existence wouldn't do anything to help her reach the original timeline or make it better.
This is the same reason I don't think Akane is sabotaging her. If he sent Nene back in time in hopes that she would fail and erase Amane, he probably wouldn't have sent her to Amane's 4th birthday. He also has the same goal as Nene: to get back to the original timeline. The only way to do that is to stop the Clock Keepers and Amane from changing anything and let the timeline progress as it did originally until the time of the school festival.
But, even with all her friends on her side, the possibility that she fails to prevent those changes and has to use time travel yet again is looking pretty likely... (as of ch. 130). So until she's safely returned to her original timeline, we can't rule out the possibility of her erasing Amane, either.
If she does, Iām almost entirely certain that the series wonāt end that way. Sheāll find some way to bring him back. It would be a terrible writing decision for the characters not to return to the original timelineāand I trust Iroās writing enough to be fairly confident itās not one she would make (Iāll talk more about this in a separate post). Of course, if Amane were erased, there would be no way of returning to the original timeline. Unless, that is, Nene figures out how to get him back. It would be really interesting to see Nene follow in the footsteps of Kako and Amane's time travels and somehow erase Amane... but if she does, I wonāt be too worried about him.
Thanks again for sharing your theories with me!! I hope this was coherent enough lol