And at least half of the others who died with them are random people who didn't go to there school so they wouldn't even know.
Here is the thing, that's not true, and absolutely incorrect.
We know there were multiple classes, why?
The Light Novel
(And I'm not talking about the Webnovel, who did not had this portion) itself mentions Aran and Izumi who were from different classes
(Although the official translation mentions, what was it again, different town or something? That was a mistranslation of theirs).
And if you say "
This is the manga, we don't argue Novel spoilers", this is Prologue of the story, I'm also talking about the Light Novel that now has an official translation, and this manga serves as an advertisement for that novel (Do support the official release)
So, without spoilers,
we can deduce at least 2 classes.
If
we assume an average of 30 students per class (Which is the usual average number of students for classes, or was it 40?), we would already be talking about 60 students + 2 teachers. That's not 1/2 (50%), that's almost 2/3 (66%, or in this case, 62/101).
Of course,
some of the students may not have gone to the ferry, either because they didn't want or couldn't
(we learn that Amamiya really wanted to go, so he did his best to get permission), so we
could reduce the average number of students from 30 to something less, but the number would likely still be around 20 at minimum, and then we would also likely expect there to be more than 2 classes.
The
Light Novel also points out that Rod did filter the people out, so the 101 were not 100% of the people on the ferry, meaning, "a number" of them really died and stayed dead, no other choice, this includes the terrorists that caused the incident.
For those who read the Webnovel,
we have 3 known teachers: Murakami (Chronos), Joseph (Druid) and Derrick (Chiron). This is only about named teachers, and there could be more. We also know a few non-school related personnel:
Mao Smith (Noah) and Jonnhy Yamaoka (Balor) were people who worked in the ferry, and Amemiya Hiroto (Braver) was a NEET who was going to his uncle's place for work, after being thrown out of his parent's house by his own parents, and just happened to be in ferry.
all of them were in a new world starting life over. The last thing they would be asking about is there past life
This is also very presumptuous of you.
Sure, those who read the webnovel should already know that this is false, but I don't even need to use that argument.
You talk as if you believe that all those people hated their previous lives or didn't care about it. They lost their family, friends (people from outside the school, besides similar aged people who weren't in the ferry), some may have lost pets.
Hell, we could even imagine some random regrets some of those people could be having, like being unable to see the rest of Berserk or One Piece
(Or some hit story that they really liked and wanted to see to the end): They will never see the end anymore.
So your presumption that 100% of them would be ignoring their own previous life, that's a very generic isekai protagonist mindset of yours.
Sure, some did take the chance to do what they couldn't before, now that they have cheats and stuff, but that's not to say there aren't those who still hold onto the memories and experience their got from the previous life.
So yeah, just by using mere logic, your presumption is very flawed.
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And for those who read the novels, of course, I don't even need to mention the name of one of the most annoying characters in the story. Everyone knows who I'm referring to.
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It however still doesn't counter point the main problem of the idea of some sort of lie having been made, and even worse, the idea that this lie would be able to persist for so long.
It's also important to note that a "Lie" and a "Misunderstanding" may be similar, but they are two different things.
Just imagine a natural situation, no need for spoilers.
Who was the person who would be searching for Amamiya (Van)? The only person would be Narumi herself, we can agree on that.
So Narumi approaches this guy with similar name, and this guy, who has no idea about her reasons or context, suddenly is approached by a cute girl who is calling his name and thanking him for some sort of action he did.
It has been a number of years, and he was indeed in the ferry, so although memory may fail here and there, she is saying it was him, even the name is the same, so as much as he may be confused,
can he deny when so many variables fit, and he may just not remember the events from so long ago? Would this be considered him lying? Or would this be considered a misunderstanding?
And finally, we get the point that, was there really no one who didn't remember him? For those who read the webnovel, I don't need to mention the answer as Van got to recently give his answer about this certain someone in the translated chapters. But even without that, we can assume that, at least by name, one person would have to at least recognize something, for example, his teacher.
The only way for this misunderstanding to resume for so long would be for both Amemiya and Amamiya to not only look similar, but to also have similar lives and behavior, for example, he would need to have been a student...
But if both were to be a students in similar classes and in the same school, it would most likely have already been known that there are indeed two people at school with similar names... Yet, it doesn't seem that they got that information... Strange, but do you catch the drift?