The story is based on comic of the same title ( 20 Seiki Shonen ) by Naoki Urasawa. The comic spanned 8 years between 1999 to 2007 and held out its last secret until the very end. This is typical of Urasawa's style, and I'm not a big fan of the way the story just seems to tease its viewers forever.
The movie and the story is solidly planted in '60s Japanese culture, especially kids who grew up in Tokyo around that time. If you're not familiar with what kids culture in Japan around that time was like, you are disadvantaged in understanding the core premise of this story. I believe that the whole concept has lot to do with Urasawa's personal experience growing up in that era.
The premise of the story is that the imagination and dreams of the kids that grew up in the '60s becomes the basis for the actual world in the 21st century. Part1 is around 1999, part 2 is around 2015, and this part 3 is around 2017 in the time line of the story. One of the eight kids that grew up together becomes the world leader, and the other seven tries to stop his dictatorship.
This is a very dark story that was popular during the first 5 years of 21st century. It's intriguing as most of Urasawa's comics are, but it may have too much of his personal taste in Japanese culture to have appeal to the global audience. My favorite comic of his was Yawara, but for afore mentioned reason, his comics became too burdensome to read.
This is kind of a cult movie, and your take on it may vary according to your taste.
