Akira is the titular main character of the Akira universe, both in the manga and the anime of the same name. He is a psychic child who serves as a key in the lives of the main characters, particularly Tetsuo Shima.
Akira is a supporting character of the anime, which was named after him. He was supposedly a young child recruited by the government for their secret parapsychology project and assigned the number 28; the purpose was to research the availability of psychic powers in humans. During this time he met the Espers and befriended them, but shortly afterward his powers grew tremendously to where they completely obliterated the original Tokyo, starting World War III. As a result, Akira was retrieved by the scientists and was presumably dissected to discover the cause of his sudden psychic growth, but was put in cannisters and cryogenically frozen underground when it failed. Akira serves as a political and influential enigma among the main characters, with considerable debate on whether he actually exists or not. Kiyoko of the Espers describes him as the ultimate form of human evolution, and the consequences of humans trying to evolve too early by taking biological shortcuts.
Throughout the film, Akira is the recurring subject of Tetsuo's quest to retrieve him and acquire his power. After discovering the boy in his dissected state, Tetsuo goes on a rampage, angry that he is not what he imagined him to be. Akira later appears in the end of the movie not as a ordinary human being, but as a spirit-like form who has transcended the limitations of a human body after the Espers telepathically summon him for help. After reuniting with his friends, Akira makes an explosion that absorbs Tetsuo, now transformed into a grotesque form of himself, and transports him into another dimension. Tetsuo's friend Shotaro Kaneda was unwittingly caught in the explosion and he experiences Akira's memories before being transported back to Neo Tokyo by the Espers.
Akira is a young child, therefore he has a personality akin to a small child his age. He gets along well with the Espers as they were fellow government test subjects, and is shown to have delight in Masaru's display of telekinetic powers. He is willing to help his friends in battling a mutated Tetsuo, even if it'll destroy Neo-Tokyo in the process.
Unlike in the adaptation film, where Akira is a supporting character, he is a main character in the manga. Akira was a child test subject, designated number 28, who was part of a secret government parapsychology project where its members tried to research the availability of psychic powers in humans. It went horribly wrong when Akira's powers went out of control and utterly destroyed the original Tokyo in a destructive explosion - out of all the child test subjects who were in the project, only Akira and the Espers (Kiyoko, Masaru, and Takashi) survived. While the Espers still lived, albeit in aged states, Akira was imprisoned in a cryogenic chamber and kept underground to avoid further disaster.
Several years later, Akira was made part of Kiyoko's prophecy that he will destroy Neo Tokyo due to Tetsuo's involvement. As predicted, Tetsuo unearths and releases Akira from his cryogenic imprisonment with the intent of using him, but when Akira is exposed to Takashi's death from an assassin's bullet meant for him, he is traumatized psychically and destroys Neo Tokyo, killing millions save for a small group people the remaining Espers saved in their efforts. He is later taken in by the Great Tokyo Empire where he is made Emperor and worshipped as a 'god' by its followers for his "miracles", but in reality his autistic-like personality made him more of a figurehead. Akira is later the subject of a failed assassination attempt by a Japanese soldier, George Yamada, and formed a psychic link with Tetsuo, which allowed both boys to not only share thoughts but also pain. During the climatic battle, Akira is shot by Ryu, a former terrorist, to stop him from destroying Earth with Tetsuo, but ends up "restoring" his former personality. With the help of the Espers and a resurrected Takashi, Akira is able to use his powers to cancel out Tetsuo's explosion and absorb him.
Akira, unlike the movie, is figuratively an empty shell of his former self; his psychic powers have increased to the point where it has destroyed his personality. He almost never speaks himself or reacts to external stimuli, making him vulnerable to the manipulations of other characters, who either seek to destroy him or take control of his abilities, mainly Tetsuo. His former friendly personality is only restored when he is shot.
Powers and Abilities
Akira has a variety of psychic powers due to being a test subject for a series of secret government ESP experiments in the 1980s, among them are telekinesis, telepathy, and teleportation. All of them have developed their potential to where they became almost god-like - even a simple act of using them is capable of doing massive destruction on a large scale. Akira presumably had lost control over his powers once in both the film and the manga, destroying the original and new Tokyo (now called Neo Tokyo) accidentally, but in the end he seemingly gained control over them.