Ability Body Crystal

Crystallized Esper Essence or Ability Body Crystal (能力体結晶) is a small red crystalline prism, that was created and overseen by Kihara Gensei as a means to achieve SYSTEM.

Concept and Creation
According to Gensei in his presentation to other Academy City researchers, overloaded espers (espers who has lost control of their powers) form abnormal synapses within their cerebral cortex. a large variety of neurotransmitters and hormones are secreted in unusual quantities. This crystallized esper essence is the product of collecting, refining and purifying those secretions.

Theoretically, applying the crystallized esper essence to selected espers, one can achieve SYSTEM or level 6. Exposing the crystal to overloaded espers with the same ability, and to another esper who has the same ability and can achieve higher levels of power when exposed to certain factors (such as Haruue Erii ), one can cause an AIM Dispersion Field Resonance thereby causing the resonance to power-up the esper, allowing the achievement of a level 6. However, such a case would cause undesirable effects to the espers, and to the surroundings as a consequence of creating a Poltergeist is likely.

First Sample
With the intent of achieving SYSTEM, Kihara Gensei uses his own granddaughter, Therestina, was used as the first test subject for the crystal, known as the First Sample. It is unknown what results were drawn out of the experiment were, though it is safe to assume that the experiment encourage Gensei even further into perfecting the crystal. Therestina lived through the experiment, but it is also unknown what affects the experiment did to her; it is known that even though she was used in the experiment, she still continued to support her grandfather, even helping him in his research as an assistant. Before the events of episode 24 of the anime, Therestina has gained possession of the First Sample, the same crystal that was created from her.

Kihara's presentation to Academy City researchers
Some time later, Kihara Gensei gives a presentation on the crystal to the city's academic community. Here, he explains how it was made and how it can be used to achieve the goal of SYSTEM. He receives the suspicion of Heaven Canceler, one of Academy City's most influential doctors, who asks him if the crystal can truly achieve level 6, which Gensei assures him it would. Heaven Canceler also asks him how many victims have been sacrificed to create the crystal, which Gensei says that there were no victims in his tests.

Child Error ability overloading experiment
Gensei had control over the Advanced Education Department, wanting to use the Child Errors there as experimental samples for his crystal, he uses the ruse of controlling the AIM dispersions of espers as a cover for his plan. He hires one of the researchers, Kiyama Harumi, to prepare the children for him for the experiment as a teacher to them.

The experiment goes as planned, however the Child Errors goes into an indefinite comatosed state after having their abilities overloaded by the crystal, Gensei forces everyone in the research team to gather data instead and them to keep quiet of what transpired in the department. Harumi is appalled by the experiment and quits shortly after, the comatosed children are then sent to various medical institutions for treatment, but are unable to recover from their comatosed state.

The same experiment was also used to develop a similar item, Body Crystal.

Poltergeist Arc

 * Main article:Poltergeist Arc

The Crystallized Esper Essence is not mentioned until episode 22 of the Toaru Kagaku no Railgun anime; here, Kiyama Harumi reveals to Misaka Mikoto, that the experiment on the Child Errors on analysing the overloading of esper abilities, was a ruse as to discretely test the crystal on the children. Harumi also states that she is looking for the First Sample, a vital part in helping her students recover from their comatosed state, without them causing another Poltergeist Incident.

When Therestina's true identity is discovered by branch 177 of Judgment, Misaka Mikoto confronts Therestina herself. After being defeated by Therestina, she reveals to Mikoto on continuing his grandfather's work on achieving level 6, and mockingly give thanks to her for finding the comatosed children for her.

In the final episode, it is revealed that Therestina has the First Sample of the crystal in her hands, and planned to use Haruue Erii, along with the comatosed children of Kiyama Harumi, to cause an AIM Dispersion Field Resonance, allowing Haruue Erii's power to be boosted by the crystal, and finally achieving level 6. Her plan is stopped by Mikoto, Uiharu Kazari, Shirai Kuroko and Saten Ruiko, as the effects of her experiment would destroy Academy City. After being defeated, Kiyama Harumi uses the First Sample to finally wake her students.