I guess I should say explain the final 30 minutes of the movie, without it sounding like a convoluted mess.
eh, I'll give it a shot.
When Kaneda and Kei are in the prison, Kei gets possessed by Kiyoko, the little esper girl. She explains that scientists tapped into the evolutionary power of an amoeba 30 years prior. These were the initial Akira experiments. Akira eventually exploded and created this blackhole-like vaccum in the city.
The Colonel is trying to prevent the same thing from happening, so he tries to put an end to Tetsuo (or at least subdue him). Tetsuo, who's been on a pill-induced high for most of the film, gets his final, painful migrane and starts to lose control of his abilities and his rebirth as a giant amoeba begins.
Kaneda, the best and only friend he's ever really had, is dead set on killing him. When he gets a clear shot, Tetsuo cries out for his friend's help. This shocks Kaneda and despite what this giant fucking blob looks like, it's still his friend.
Meanwhile, the espers are trying to channel Akira's spirit to stop and encompass Tetsuo's explosion.
Then the craziest thing happens. Akira returns. He basically wills himself back into mere existence to help his childhood friends and save the world. With the knowledge of how to control his power, he envelopes Tetsuo's explosion.
Tetsuo cries for his friend's help and uncontrollable absorbs Kaneda.
Then he gets further sucked into Tetsuo's psyche and re-experiences some of his long-buried memories. One of the most important being that as an orphan,
Kaneda was his only friend.
Having saved the Colonel and Kei, the espers then sacrifice themselves to bring Kaneda back, too.
After most of Neo Tokyo is destroyed, we're left with the final words, "I am Tetsuo." While this is open to interpretation, I just think it means that he's transcended to the same form of existence that Akira's reached.
To me, the main thing this film is about is friendship. Tough-love, strong-bonded friendship. I've watched a stupid amount of times, but each viewing leaves me with something new. It's just so super-saturated with details. If I've misinterpreted anything or anyone has something to add, please do. Yeah, it's a little convoluted, but it makes sense after about a billion viewings. >;P