The central twist of "Akira" is that the titular character, hyped as a messianic figure or a source of ultimate power, is not a conscious being waiting to be awakened. When Tetsuo finally reaches the cryogenic chamber beneath the Olympic Stadium, he discovers that Akira's body was dissected for scientific research after the first apocalypse. The 'power of Akira' is a raw, uncontrollable force of creation and destruction, and Akira was merely the first child who failed to control it. Tetsuo, in his quest for a being he thought he could dominate or ally with, finds only vials of organic matter, leading to his psychological breakdown.
Tetsuo's powers, a result of his encounter with the esper Takashi, are shown to be of the same nature as Akira's. His inability to control this power leads to his grotesque final transformation. His body, no longer under his conscious control, mutates into a gigantic, amoeba-like mass of flesh and technology, absorbing everything around it in a horrifying display of body horror. During this mutation, he accidentally crushes his girlfriend, Kaori, a moment that signifies the complete loss of his humanity.
The enigmatic ending sees the other three espers—Kiyoko, Takashi, and Masaru—triggering the release of the power contained within Akira's remains to stop Tetsuo's rampage. This creates a singularity, a miniature big bang, that engulfs both Tetsuo and Kaneda. Inside this alternate dimension, Kaneda experiences flashbacks of his and Tetsuo's childhood, highlighting the friendship that was tragically destroyed. The espers rescue Kaneda, explaining that Akira has taken Tetsuo to a safe place. The singularity then vanishes, leaving a massive crater where Neo-Tokyo once stood, now filled with water. The final line of the film, "I am Tetsuo," spoken from this new plane of existence, implies that Tetsuo has not died but has transcended to become the creator of a new universe, finally achieving the ultimate power he sought, but at the cost of his world and his physical self.