Hakurei Reimu hadn't predicted Gensokyo's end—saying that would be a lie. In fact, she was the only one knew about it since she could remember, and accepted it on top of that. Because nothing could be done about it. It wasn't because she didn't have enough strength. It was because the system called Gensokyo had an end built into it from the beginning. Because Reimu was the one who regulated the Hakurei Border, she understood that fact. Gensokyo was a paradise separated by the Hakurei Border.
To put it another way, that boundary line was necessary and when it collapsed, Gensokyo would end. Because if the inside and the outside became one, it would cease to be 'fantasy.' The dream world where things that were lost ended up was able to exist because it was separated. A contradiction was born there. The Hakurei Border had a hole in it. A small hole. A hole people sometimes wandered into, items flowed into, and things that had become fantasy in the outside world arrived at. Going through the hole from the outside to the inside, fantasy became reality. That was Gensokyo's origin and the way it existed. Then—what would happen if that continued? Items would stream in. People would stream in.
The outside world would continue to change, and Gensokyo would continue to be filled. The difference created would become greater the more time passed. The way water fell from high places to low places, the things that were lost in the outside world would continue to flow into Gensokyo. There would be a problem with Gensokyo's space. Into the world that had a limit and was separated by a border—fantasy would continue to flow. The flow would not stop. In the outer world, humanity finally reached the moon. The way rockets required vast amounts of fuel, the many things that were cut off to reach the moon were forgotten, and all of them became fantasy and flowed into Gensokyo. Fantasy would push against the tightly packed world and get in even if that meant forcing the hole to widen. As a result, the world would—To explain it with words, that was all All that happened was what happened to everything. It was born, and it would die. That wasn't only for humans—even worlds weren't exceptions. As long as the world called Gensokyo was one that had been born, it would die one day. It was possible to forcefully prevent that. The way the girl who drank the Hourai Elixir became unable to age or die, it was possible to stop the natural order of being born and dying. It would be simple. If fantasy was coming in through a hole, one just had to close it. Just as Thkari and the Hakurei shrine maiden closed man-made holes, one could close the hole that was naturally open, close all the holes—and truly isolate Gensokyo. II one did that, at least the things from the outside would not come in and rupture it.
But, if the laws of nature were twisted hentai, a distortion would be created. If all the holes were closed, Gensokyo would suffocate. A paradise in which nothing new was created and was completely closed off was the same as one that was dead. Simply repeating the same things, and while repeating them—it would slowly rot. That was one form of paradise, and at the same lime, an end. Dreams ended, and a sleep that was not woken up from was the same as death. Either way, an end would come. The difference would be whether it was a natural or a distorted one. That was why the Hakurei shrine maidens protected the bordei for generations. Until the day it collapsed, while passing the role down generation after generation, together with the unchanging