Silent Party

Silent Party is the term used by STUDY to refer their large-scale "rebellion" against Academy City to force the city into a paradigm shift from espers produced through the standard Power Curriculum Program to their own process through the use of artificial humans, also known as Chemicaloids.

The Silent Party occurred in late of August of the story's first year. It was a disastrous attempt at a rebellion, as despite the 20,000 and more Powered Suits used for it as well as 2 mobile weapons piloted by two STUDY members themselves, they were unable to escape the Academy City Research Exhibition Assembly venue at all due to the efforts of several members of Judgment and the coincidental appearance of two Level 5s. Tragedy would've been the aftermath however after STUDY launches the AIM bomb on Academy City, but this too proved to be futile as it was stopped by Misaka Mikoto.

Background
Aritomi Haruki, the leader of STUDY, became disillusioned with Academy City after realizing that no matter what accomplishments a genius like him would get, his recognition paled in comparison to the espers, of which the city pours all its attention to.

One day, Aritomi thought about the uncertainty of the nature of esper power development, which is largely determined at birth, and how the production of high-level espers are based purely on chance. This uncertainty was something that Aritomi decides to eliminate by making an esper from scratch (i.e., making an artificial human being that possesses esper abilities). A new method of producing espers based on a completely different approach, a more reliable method to produce espers of a uniform quality, and as many as anyone could ever want, thus begins the Chemicaloid Project. Haruki joins up with several like minds to come with the plan, and presented it to underground organizations to gain their support. However, they did not see its worth, and among them, Kihara Gensei, whose Level 6 Shift Project would have become a competitor against their project, even called their plans a mere "summer school project." Dismayed by this, they determined to do the project on their own. Aritomi and his colleagues soon established the STUDY Corporation, and with their technology supplied Anti-Skill of their tools, and manufactured drugs and other chemicals of a wide spectrum. Most likely, these are fronts to fund their project. Later, their Chemicaloid Project bore fruit with Janie and Febrie, the former having the ability known as Diffusion Ghost, this ability was used by STUDY for the purpose of controlling Powered Suits.

STUDY preparations
STUDY decided to invade the venue for the Academic Assembly, and from there attack Academy City. To do this, they required the use of 20,000 and more Powered Suits, as well as a few mobile weapons. The suits were delivered to the venue through legal channels, though information regarding its contents were blocked through power outages. STUDY has already prevented any sort of investigation on them by Anti-Skill as they are the ones providing them tools. The Powered Suits and Janie's power, Diffusion Ghost, were tested a couple of days prior to the attack, including testing on Mugino Shizuri and Misaka Mikoto, two of Academy City's Level 5s, allowing them to make improvements on their plans.

Moreover, STUDY itself actually believed in the possibility that their plans would go awry, and as such inserted the AIM bomb on the orbital station of the Endymion 35,000 kilometers above the Earth's surface, apparently with Academy City authorities none the wiser. According to Haruki, the bomb can destroy Academy City.

Counter-preparations
The only organization that has shown any apparent care for STUDY is Judgment, specifically, Judgment 177 Branch Office, an office with close ties with Misaka Mikoto. The branch has been against STUDY ever since discovering their involvement with Febrie, and after discovering the full extent of their plan they began making plans of their own despite their dire odds. Mikoto followed Nunotaba Shinobu's plan to continue her watching over Janie, Febrie's sister, despite already having betrayed STUDY. This is because one of their primary goals was to save Janie. Following this, the group can only wait for Janie to activate her powers in order for Febrie, who has the ability to track her sister whenever she uses her powers, to track her down. This means that the group can only make their own after the Silent Party has already begun.

To even their odds, Kongou Mitsuko, one of Mikoto's friends, asks her father the President of Kongou Aviation Industry for the Ekaterina II S, a large transforming mecha. Kongou later gives the manual on how to operate it to Saten Ruiko and Uiharu Kazari, two of her middleschooler friends. Yomikawa Aiho, the only known member of Anti-Skill sympathetic to their cause, is later tasked in delivering the mecha to the battlefield. Moreover, Uiharu Kazari would later take over a few Security robots to the battle. Finally, Konori Mii, the chief of Judgment 177 Branch Office later asks her friend Yanagisako Aomi to rally other Judgment members to their cause and is successful in doing so.

They are later separated into five groups: Misaka Mikoto and Febrie; Uiharu Kazari and Saten Ruiko; Shirai Kuroko; Konori Mii; and Kongou Mitsuko, Wannai Kinuho, and Awatsuki Maaya. The latter four groups were to guard the entrances to the assembly and prevent the Powered Suits from escaping. Mikoto and Febrie on the other hand were to wait for the activation of Janie's power and track her down. The latter four groups in the assembly venue would later be joined by the other Judgment members. The members of Judgment were to stall the Powered Suits through sheer numbers, while the known espers present, specifically, Kuroko, Kongou, Kinuho, and Maaya were to attack and destroy them. Here, their battle plan basically consisted of preventing the Powered Suits from escaping until Mikoto can defeat STUDY and free Janie.

Break of dawn
The attack starts at the break of dawn, with 20,000 Powered Suits controlled through Diffusion Ghost trying to pour out of the four entrances of the Academic Assembly venue. With Janie's powers activated, Febrie can now locate her sister's location, at which point Mikoto began her movie. Meanwhile, the Powered Suits pause before the girls, as STUDY sees them through their computers and mocks their efforts. They however, are later surprised by the sudden arrival of Judgment. Thus, the counterattack against has Silent Party begun.

The Judgment members attack in force, using polearms to assault the Powered Suits and riot shields to defend themselves. The groups have a communication network allowing for them to relay information and instructions As for the espers, Kuroko uses the javelins she has to attack the Powered Suits, Kinuho and Maaya take advantage of the Powered Suit's simplistic AI to draw them away, and finally, Kongou would use her powers as traps prepared for the drawn Powered Suits. STUDY on the other hand is initially unperturbed by their efforts, that is until Misaka Mikoto finally found their base of operations for their attack. Haruki though surprised, tries to boast to him of their power, and orders countless Powered Suits to attack her. Although Mikoto is delayed by the sheer number of Powered Suits, Mikoto is easily able to destroy several of the Powered Suits.

STUDY counterattack
With their opponents actually gaining ground, Haruki orders to use their counterstrategy, apparently preparing for just such a possibility. With this, the communication system of Judgment goes down, as so does Kazari's control over her security robots. Kosako Shunichi and Madarame Kenji are then sent to attack the now defenseless Judgment members in one of the venue entrances, where Ruiko and Kazari were. Meanwhile, Mikoto continues to fight the Powered Suits but is slowly being worn down by their number. She is then forced to fight mobile weapons that uses an attack that is based on Mugino Shizuri's Meltdowner.

End of the party
However, STUDY was not prepared for a couple of coincidences occurring in the battle. Yomikawa Aiho finally delivers the Ekaterina II S to the battlefield. Before the mobile weapons Shunichi and Kenji can make any apparent significant damage, Aiho delivers the mecha to the venue, temporarily knocking out the two mobile weapons, allowing for Kazari and Ruiko to board it. Moreover, she also brought along Haruue Erii and Edasaki Banri, allowing for them to form a communication network using the telepaths present in the battle. Then, with the Ekaterina II S fully mobilized for battle, the mobile weapons were no match for the piloting skills of Ruiko and Kazari and were easily defeated.

Meanwhile, as Mikoto is struggling with the Powered Suits and the mobile weapons, help coincidentally arrives from an unlikely source: Mugino Shizuri and ITEM. Still angered by STUDY's use of her and her team as a guinea pig for their Powered Suits, ITEM attacks Powered Suits and mobile weapons gathered at the stadium. Despite Mugino and Mikoto's antagonism towards each other, the two do not hinder each other during the attack, allowing Mikoto to go further into STUDY's base of operations.

AIM bomb
With the battle turning ill towards them, and now that Misaka Mikoto has finally arrived before them, in a fit of despair Haruki launches the AIM bomb. The launching of the bomb however deactivates the Powered Suits as the system which Janie is in to go out of control, making any sort of connection impossible as it will kill her. With everything they've built undone in a single morning, Haruki tries to shoot himself but is saved by Mikoto. Afterwards, Sakurai Jun tells Mikoto of the AIM bomb, their last resort for when their plans fall apart.

Though the ground battle is finished, the danger has still not subsided. Mikoto calls for a meeting on how to stop the AIM bomb, where it was decided that they can use the Ekaterina II S as a weapon to destroy it, though the only problem is on how to launch it into the upper atmosphere. Here it was decided to have Kongou Mitsuko's power, the Aero Hand, to launch it, though the specifics to launch it safely has not been calculated. Although they try to find intelligent members of Judgment to aid in the calculations, Kazari concludes that they need a supercomputer for the calculations. Mikoto is later contacted by the Sisters, and use their brainwave network, the Misaka Network, to do the calculations. With that finished, Kongou and Kinuho apply their powers on the Ekaterina II S according to the specifactions they have been provided with. Misaka Mikoto and Shirai Kuroko strap into the machine inside, intending for Mikoto to shoot the missle down with her Railgun using the mecha for her ammunition, and Kuroko to be the one to teleport her back to safety.

With everything ready, Kongou activates her powers and the mecha launches properly into the upper atmosphere. There, Mikoto uses her powers to shoot the mecha towards the AIM bomb, destroying it. The aftermath of this is that debris from the explosion causes it to rain down on Academy City.

At the same time as this, to free Janie from the run away system, she has Febrie call out to Janie due to their "strong emotions," as they share the same biological base. A plan that Saten Ruiko says is pretty much the "power of love." Her untested plan is successful, with a little help from the Sister clones, stating that Janie and Febrie are like sisters to them as well, giving the computers a boost to allow Febrie's emotions to reach Janie. She later awakens, and Febrie greets her a good morning. She later witnesses Shinobu breaking down in tears for the long burden she had to put up with is finally over. Thus ends the Silent Party.

Aftermath
There are no apparent casualties on either side. Of the Academic Assembly, it occurs as planned on the same day as the Silent Party, though there have been a delay and it is unknown if it involved the Silent Party. It is unknown what happened to the members of STUDY aftewards, though it is likely that they have been taken into custody.

Investigations on the Silent Party have been tampered with to give a favorable view of Mikoto and her group. Mikoto used her powers to manipulate the digital records, while Shokuhou Misaki, the 5th-ranked Level 5, used her powers to brainwash the authorities. This is only after Mikoto, who is usually antagonistic to her and her powers, laid down her pride and asked for help.

Of Janie and Febrie, they later leave Academy City for external facilities with Shinobu to readjust their bodies, similar to most of the Sisters. It is unknown what opinion Academy City has on Chemicaloids after the incident.