An RWD sports sedan launched by Toyota in 1998. In Japan, it was sold under the name of Altezza, Outside Japan, it was sold under the name Lexus IS (first generation) as a competitor to the Mercedes-Benz C-Class and BMW 3 Series. Since the Altezza was intended for the D-segment market in Europe, it had a sedan body that emphasized practicality and comfort, but it also featured a short overhang body with excellent turning performance and a four-wheel double wishbone suspension that excelled in handling performance despite its high cost. In reality, the Altezza was a sports car in the shape of a sedan. The Altezza was also equipped with the famous 3S-GE engine, which had won numerous victories in F3, WRC, JGTC, Pikes Peak, and other races, and Toyota gave its dynamic performance on par with that of a sports car. As a result, the Altezza achieved good results in racing as the base vehicle for racing machines, including a long reign as class champion in the Japanese endurance racing series. The Japanese tuning industry greatly welcomed the Altezza, which was born as a sedan that was as close to a sports car as possible, and a wide variety of tuning menus were developed, including retrofitting turbochargers and engine swaps, and the car gained a great deal of support from Japanese car enthusiasts.

The setting is a huge city with a total population of just under 2.3 million, occupying most of the western part of Tokyo. It is called "school city" because about 80% of its population are students. Students in the school city had a special curriculum to develop supernatural abilities, and were assessed on a six-level scale from "no ability" (level 0) to "supernatural ability" (level 5) according to their abilities. The main character, Kamijou Touma, is a high school student in school city, but his assessment is incompetence (Level 0), on the verge of failing. Because in his right hand, He had an ability called "Imagine Breaker" in his right hand, which cancels out any other power. He had just started his summer vacation. On the first day of summer vacation, a sister in a pure white nun's uniform suddenly fell from the sky in his room. The girl said, "I am a magician , I had escaped from the world of magic." She calls herself "Index" (Index of Forbidden Books), and the "sorceress" appears in pursuit of her. The sorcerer's goal is the 103,000 grimoires in Index's head. In the battle he is forced to get involved in, he destroys the magic that has been cast on Index with his right hand, and in exchange for freeing her from her sad fate, she loses her memory.　 Touma spends his days trying not to let people know that he has lost his memory, but... Incidents befall him one after another. In order to save Mikoto Misaka, the "Electromaster," the third most powerful person in the city, from a tragedy, he is forced to defeat the "Accelerator," the first ranked "one-way street" in the city, In order to save "Electro-Master" Misaka Mikoto from a tragedy, she has to defeat "Accelerator", the No. 1 ranked student in the school city, and also has to confront a magician who is planning a confrontation between the "science side" and the "magic side". One day soon after the start of the second semester, Toma is involved in a new and even bigger case. When "science" and "magic" cross paths once again, the story begins. The story begins.

She is 14 years old and attends Tokiwadai Junior High School, one of the five most prestigious girls' schools in the city. She is the third of only seven "Level 5 psychics" in the city, and is an "Electromagnetic Master" who can manipulate electricity at will. She is also known as a "super-electromagnetic railgun" for her ability to launch coins at three times the speed of sound through the application of electromagnetic force. She and Kamijou, whom she met in an incident, have a foul-mouthed relationship that comes to hit out every time they meet. She is very straightforward, and while her behavior is not typical of a young lady, she has a penchant for fancy goods and cute clothes, She also has a girlish side to her.