Tetsuo (born July 23, 2004), full name Tetsuo Shima (島 鉄雄 Shima Tetsuo), is the main antagonist of Akira. He evolves from Kaneda's best friend and gang member to his nemesis. He is involved in an accident at the very beginning of the story, which causes him to display immense psychic powers. He is soon recruited by the Colonel and became a test subject known as No.41 (41号 Yonjūichi-gō). It is mentioned that he is Akira's successor; however, Tetsuo's mental instability increases with the manifestation of his powers, which ultimately drives him insane and shatters his friendship with Kaneda. Later in the story, he becomes Akira's second-in-command, before he begins to lose control of his powers. Eventually, Kei battles Tetsuo, unlocking his full power and triggering another psychic explosion. Akira, watched by his fellow Espers, absorbs Tetsuo's explosion by creating one of his own. With Akira and the espers, he ascends to a higher plane of existence.