sir_mihael said:
I think the important thing is not to consider 21st Century Boys as a sequel so much as the TRUE final chapters of 20th Century Boys. I have no idea why Urasawa renamed the series for these last books, because it does kinda make the last chapters of 20CB seem a bit vague.
But yeah, so long as you move straight onto 21CB it's fine.
Saying that though, even after reading the end of 21CB, there's still a few things that didn't get completely cleared up that I would've liked, but nevermind, this is still one of the best Manga I've read in my life. XD
My thinking is that Urasawa renamed the series 21st Century Boys in order to reflect what has happened in the story. 20th Century Boys, ended with their own Woodstock, which sort of marked the end of an era. In other words, it's time to move on than stay stuck in the past, thus the transition to the next century.
It's also important to remember that most of the events in the story took place in the 21st century and not the 20th. Friend's rise to power put an end to modern history and as we saw, a stop to progress. Thus, everyone was stuck in the past, the 20th century, and could not see the future that they had dreamed of in the 21st century. Friend's downfall, allows mankind to transition into the future, and thus the 21st century.
All in all, I felt it was a clever way to incorporate the title of the story into the overall theme of the manga.