The third season of Toaru Kagaku no Railgun. 

The Daihasei Festival has begun, and that of course means that Tokiwadai Middle School—a prestigious all-girls' middle school—is competing too. Despite the participation of the "Ace of Tokiwadai," Mikoto Misaka, the other students who are participating are still putting their utmost effort into winning, no matter how impossible the feat may seem against her might. 

However, not all is fun and games. Due to the festival, Academy City opens to the outside world, and various factions have begun plotting ways to infiltrate the city. Misaka appears to be on their radar, and as the festival proceeds, people lurking from the shadows begin to emerge... 

Toaru Kagaku no Railgun T brings back the Tokiwadai Ace and her friends as they dive deeper into the dark side of Academy City. From terrorist attacks to ruthless underground projects, anything is possible in this city. 

(Source: MAL Rewrite)

The second season of Toaru Kagaku no Railgun. 
 
Something sinister is going on in Academy City. The shadows are filled with whispers of an organization cloning super-powered students known as espers. High-ranking master of electricity, Mikoto Misaka, laughs off these stories until she comes face to face with a copy of herself. After learning that these clones - her sisters - are being systematically murdered in a series of experiments designed to turn a sadistic killer into the strongest esper in history, Misaka vows to save her copies and destroy the organization responsible for the project. 
 
As Misaka prepares to face off against the organization’s power-hungry esper, she discovers that she wasn’t the only victim of the scientific forces conspiring within the city - and that’s something Misaka and the girls of Judgement simply won’t stand for. 
 
(Source: Funimation)

Hokaze Junko, one of the top “handmaidens” of Shokuhou Misaki, has always blended into the background of Tokiwadai–an easy feat when you go to an all-girls’ school full of powerful psychics. But when a ghostly figure starts stalking her, Junko is suddenly the center of attention! As Junko investigates her stalker, she starts to learn new things about her classmates…and herself! 
(Source: Seven Seas Entertainment)
 
Note: Includes 1 extra chapter.

Toaru Kagaku no Railgun T specials that were released on the 1st and 5th Blu-ray and DVD releases.

Keitz Nokleben