I don’t see what’s so tough to understand about Akira. I had to watch it a time or two to figure it all out, but it’s not much harder than, say, 2001, or Donnie Darko, or any number of similar American movies. It’s not immediately obvious what’s going on, but it only takes a little effort tp put all the pieces together. Here’s what I understood about it, although bear in mind that I haven’t seen it in several years, I’ve only seen the dub, and I’ve never read the manga nor any secondary sources. So a lot of this could be wrong.
Basically, there’re these children who are the next step in human evolution: powerful psychics. For the most powerful of them, their human bodies are just chrysalids: once their powers fully mature, they no longer need physical form, and evolve into… well, something else. Pure energy, star children, whatever. The movie doesn’t take us that far.
Now, some few years prior to the beginning of the movie, the government found out about these kids, and pu them into a special school where they could study their powers, presumably with an eye towards using them in some sort of weapons program or espionage capacity. The most powerful of these kids was the titular Akira. Unfortunetly (and perhaps as a direct result of government tampering to make him even stronger, sooner) Akira manifested his entire potential, and destroyed Tokyo in the process of his evolving to whatever comes next after human beings. The rest of the kids in the program lived, and were apparently given some sort of drugs or treatment to prevent them from doing what Akira did: that’s why they look so strange. They’re people in their forties (or so) who have been artifically held in childhood.
One of the kids escapes, and crosses the path of Tetsuo, a biker juvenile delinquint. The feds come in to grab him up, and take Tetsuo, for reasons I’m not entirely clear on. Possibly because he was injured, and they were just going to render medical aid. But it turns out that Tetsuo is a latent psychic himself, the most powerful one discovered since Akira went thermo-nuclear. They hope to activate his psychic powers and control him the way they control the other kids, but they blow it. His powers activate and he busts his way out of the government installation, and goes on a rampage, avenging himself on society in general for a life of being poor and bullied. But the more he uses his powers, the more powerful he becomes, and soon he can’t control himself anymore. He starts the same transistion Akira went through. This is the bit where his body starts growing big fleshy tentacles. He figures out (through telepathy, or precognition, or something similar) that the government has been storing the human remains of Akira under the Olympic stadium, and tears the place apart trying to find an answer to what’s happening to him. I’m not sure what the remains signify. Possibly, when Akira underwent his transformation, he was killed before he could complete it. Tetsuo is more succesful: he completes his evolution, and ascends to a higher plane of exsistence. The remaining kids from the program, who have had years of practice with their powers, are able to observe and somehow tag along on his coattails without undergoing a radical mutation. By the end of the movie, they’ve all ceased to exsist as humans, and have become, for all intents and purposes, gods.
That leaves out a bunch of stuff, of course, such as the resistance movement, and the entire Kaneda sub-plot, but that stuff should be fairly clear on its own. It’s a good little movie, and even without the plot, is plenty entertaining just on the strength of its visuals alone.