Accelerator

The Accelerator is a mysterious, unnamed figure whose name refers to the 1st-ranked Level 5, the strongest esper currently residing in Academy City. His journey to a more "heroic" role progresses after meeting and saving Last Order, and is forced into an ironic twist of fate where his life now depends on the Sisters, clones he previously killed by the thousands. He is forced to deal with the cruel Dark Side of Academy City and the secret conspiracies surrounding it. As the most powerful esper of Academy City, his existence and powers are tied to the plans of Aleister Crowley, the founder of Academy City, alongside Kamijou Touma. Ever since taking the Power Cuuriculum Program, and realizing his powers, Accelerator was sent to a "special class", and spent much of his childhood there until nine years old, before being moved into another special class. Both of these had him as the only student. It can be presumed that this occurred before the incident involving the military.

When Accelerator was a child, he couldn't fit in with the other children due to his powers, harming those that tried to get close to him. Around at the age of ten, a particular incident with children escalated with Academy City being deployed against him, and he later "gave up", and was sent to a special class. This has made him something of a loner and distrustful towards other people. After some time, Accelerator was discovered by Kihara Amata, who trained him how to control his powers and influenced him enough for Accelerator to adopt his personality. It can be assumed that the Dark May Project started after Accelerator acquired the cool personality he now has from Amata.

Accelerator's ability made him the subject of an experiment attempting to create the first Level 6 Esper; according to the city's best supercomputer, Tree Diagram, this feat could only be achieved by killing The Railgun, 128 times. However, because it was impossible to create 128 of these 'railguns', due to the 'Level 5 Mass Production Plan' only being capable of producing a sub-standard clone of Mikoto at a power of Level 2-3, a substitute plan was arranged where Accelerator would have to kill 20,000 Misaka clones in a variety of methods. He willingly joins the experiment to gain a reputation as the most powerful and feared esper so that no one would be foolish enough to challenge him ever again. By the beginning of the Sisters Arc (index), Accelerator has already killed the first 10030 Misaka Clones and during the course of the arc, kills clone 10031 before the experiment is ultimately stopped.