Level Upper Arc

The Level Upper Arc or the Level Upper Incidents is a story arc that occurs within the Toaru Kagaku no Railgun manga and anime. It is the first story arc that occurs within the Toaru Majutsu no Index universe. It focuses on the Level Upper, a device that is sought out after by many people in Academy City as a means to easily gain powers. It is also a city-wide event that affected many espers and occurs during the middle of summer season.

Background
Kiyama Harumi an AIM researcher was in charge in teaching in Child Errors as a part of an experiment, she eventually grew close and bonded with her students. During the experiment on the overrunning of abilities on the her students, a planned incident by Kihara Gensei occured and the children were injured and has put them in a comatose state. Harumi was horrified on what happened to her students she quits her job in the institute she was working in and was determined to cure of them of their affliction.

Creation and Conception
Harumi still determined to help the children requested 12 times for the use of Tree Diagram to perform a calculation but is denied permission every time, however she discovers the incredible computational powers of that the Misaka Network provided due to the 20,000 minds of the Misaka clones and opts to create her own. After researching material on synesthesia she creates a sound file to stimulate the brain and alter it's brainwaves, she also creates a treatment program for it. It is unknown how she distributed the file, though the file can be obtained by either buying it from sellers or accessing it from internet sites.

Principles
Using the Level Upper alters the brainwaves of the user to a close pattern that of Kiyama Harumi through synesthesia. The users are then connected through the use of their AIM dispersion fields using the similar brainwave patterns as a common protocol, this network is called the Level Upper Network and is controlled by Harumi. People who uses the Level Upper also gain abilities or make the abilities they already have stronger, this is because they are connected to the Level Upper network and are then able to compensate for their lack of processing capability through the use of the network. The one controlling the network is also capable of accessing all the abilities of the users who are connected to the network. However, using the Level Upper causes the user to be put in a comatose state.

Losing control of the network causes the consciousness of its users to form a being using their AIM dispersions, this phenomena is called an AIM Burst. And causes painful convulsions to the unconscious users when it occurs, it is described as being tormented by a terrible dream.

The Level Upper as an urban legend
The distribution of Level Upper has become widespread enough for people to have taken notice and use it, however it was not enough for people to take it seriously. The existence of Level Upper was simply an urban legend propogated by people and websites on the Internet, though this may have caused interest in people and may have made them seek and confirm the existence of the Level Upper themselves.

Criminal activity increases in Academy City
Before it's existence being confirmed by the authorities, many espers of Academy City have already used it and have now gained ability. Criminal activity has increased as a consequence of having, often low level espers especially delinquents gain abilities in a short period of time.

The Graviton Bombings
Kaitabi Hatsuya, a level 2 esper uses the Level Upper to strenghten his "Graviton" ability. Using aluminum materials stuffed inside mundane objects such as dolls, he creates miniature bombs that causes massive amounts of damage. Before his capture, Hatsuya injured nine members of Judgment. His last bombing occured in the Seventh Mist mall, using the highest output of his powers. The bombing made significant damage in a clothes botique of the mall, but made no casualties due to the effort of Kamijou Touma. Hatsuya was later taken into custody by Shirai Kuroko with the aid of Misaka Mikoto.

Confirming the existence of the Level Upper
The power produced by Hatsuya's bombs created discrepancies in the databanks, as his level was insufficient to produced that much power. Judgment, following the rumors of a device that increases the level of an esper in a short period, they confirm its existence but are unable to obtain the Level Upper. It is later discovered that many espers such as Kaitabi Hatsuya has collapsed and has become unconscious, they are later confirmed to have been users of the Level Upper.

Crackdown on the Level Upper
The prevention of the spreading of the Level Upper, the recovery of the comatose victims, and the arrest of the developer of the Level Upper are the top three priorities of Judgment as highlighted by Kuroko. During this point in time the use of the Level Upper has become widespread, and a considerable amount of criminals using their newly gained powers have also increased which strained the authorities considerably. Judgment has also taken protective custody of its user due to it's side-effects.

End of the Level Upper Incidents
Saten Ruiko, a close friend of Judgment member Uiharu Kazari collapses after using the Level Upper. In the anime her collapse forces Misaka Mikoto, the third level 5 esper to aid Judgment, as she blames herself for being insensitive to the feelings of its users, especially Ruiko who is a level 0, that was told by Mikoto that levels and abilities are nothing. With the help of the Heaven Canceler, Judgment figured out that the brainwaves of the Level Upper users all have the same pattern and are able to pinpoint Kiyama Harumi as the culprit behind the Level Upper. Mikoto goes after Harumi, Kuroko stays behind as she is still recovering after her encounter with Trick and other Level Upper users. At the same time as this, Uiharu Kazari is kidnapped by Harumi after discovering her plans, she gives her the treatment program for the Level Upper and tells her the reason why she developed the Level Upper. Harumi is later forced to stop the car because of ann Anti-Skill barricade. The Anti-Skills demand Harumi to surrender but is surprised by Harumi having abilities, they are easily overwhelmed by her powers and are defeated.

Misaka Mikoto vs. Kiyama Harumi
Misaka Mikoto reaches Harumi and forces to her into a battle, initially Harumi had the upperhand as she controlled many abilities at the same time. However, she is tricked by Misaka Mikoto and is electrocuted by her, defeating her. Mikoto electrocuting Harumi allowed her to access her memories and the true reason why she developed the Level Upper.

Misaka Mikoto vs. The AIM Burst
Harumi regains consciousness and suddenly loses control of the Level Upper Network, this causes the birth of an accumulation of the Level Upper user's AIM dispersions, an AIM Burst. Mikoto attacked the being but it regenerates and becomes larger. All the while, the comatose victims of the Level Upper experience suddent convulsions after the AIM Burst manifested itself. After saving Tessou Tsuzuri from it, Mikoto is then told that the AIM Burst is heading for a nuclear testing facility which makes the situation even more dire. Harumi aids Mikoto by telling her that the Level Upper treatment program can help stop the AIM Burst. Uiharu Kazari with the help of Tsuzuri and Yomikawa Aiho plays the program(as it is a sound file as well) all over the city and calms the comatose victims down which stops the AIM Burst from regenerating. Misaka Mikoto is then able to use her railgun to destroy it's core, destroying the AIM Burst in the process.

Aftermath
Kiyama Harumi is apprehended by Anti-Skill shortly after the battle, she is however still determined to cure her students and gladly challenges Mikoto that she is welcome to try and stop her again. All comatose users of the Level Upper have began regaining consciousness as well. Many users of the Level Upper are given special lessons, here they learn the basics of ability development and are trained to surpass their limits.

List of Notable Level Upper users
Kiyama Harumi estimated that Level Upper users number around 10,000, which to her was a sufficient enough replacement for the Tree Diagram.

The list of notable users below are listed in alphabetical order.
 * Akemi


 * Elder Sister


 * Jufuku Miho


 * Kaitabi Hatsuya


 * Koujun Kikuhiko


 * Kushiro Katabira


 * Mako


 * Muu


 * Okahara Ryouta


 * Saten Ruiko


 * Trick

Trivia

 * In the Toaru Kagaku no Railgun manga, the blackout caused my Mikoto due to fighting Touma on a bridge after failing to get information on the Level Upper is the same event that appears in the beginning of Toaru Majutsu no Index. This event was completely changed in the anime adaptation as Mikoto caused the blackout while fighting Elder Sister, the anime still indicates that Mikoto fought Touma on a bridge which implies that in the anime's timeline, there were two blackouts that were caused by Mikoto.