A mysterious gem called the Skull Stone is said to be able to reveal the location of the largest vein of gold in the world. This legend has entranced many people who wanted to get their hands on fame, power and wealth, including the trio of villains in this show: the Dorombo Gang. However, their hunt for the Skull Stone is not as easy as they imagined, mainly due to the faulty information they receive from their leader, and most of all, by a justical duo of pursuers called the Yatterman! (Source: Wikipedia)

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 overwhelming 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.

Throughout history, an elite group of shrine maidens known as Toji have saved the world from Aratama, strange and malevolent beings bent on destroying humanity. In modern times, these warriors have been assigned to a special police squad to exterminate Aratama. The government has also set up five elite schools across the country to provide young girls the necessary sword fighting skills to eradicate these monsters and eventually join their fellow Toji in protecting the world. A student of one of those five schools, Kanami Etou is chosen to represent Minoseki Academy in a sword fighting tournament, where she meets the mysterious Hiyori Juujou. Although Kanami and Hiyori rise to the top of the tournament, their battle takes an unexpected turn, throwing the world of the Toji into chaos. Likely that the Toji are facing betrayal from within, the two are forced to flee the tournament, clashing with former comrades on the way.

In a special jurisdiction area built in Tokyo Bay commonly known as the 24th Ward, the population enjoys a very safe life thanks to the Hazard Cast—a surveillance system that predicts accidents and assists victims immediately. However, the system cannot foresee the exact nature of these accidents nor prevent them from happening. Ran Akagi, Kouki Suidou, and Shuuta Aoi—a trio of friends nicknamed RGB due to their hair color—experienced the tragic nature of these limitations when Suidou's sister Asami passed away in a fire at her high school. A year later, Shuuta still blames himself for failing to save Asami, while Ran pursues his dream to become a famous street artist, and Kouki works in the Hazard Cast intervention unit. After the RGB trio reunites at a commemoration for the victims of the school fire, each of them receives a mysterious phone call. Bewildered to hear Asami's voice, the three friends are shown images of the future and asked to choose between two grim alternatives. Refusing to be bound by predetermined outcomes, the three tackle this troubling event head-on, marking the beginning of a series of cruel dilemmas that they will have to overcome in order to protect the 24th Ward and its people.