Three Stories Arc

The Three Stories Arc is a story arc that occurs in the Toaru Majutsu no Index storyline. The arc focus on three separate event that happen on August 31; two stories focuses on Touma dealing with magicians while the other focuses on Accelerator dealing with the aftermath of the Level 6 Shift, which would mark the first time Accelerator is featured as a protagonist to the science side.

Aftermath of Level 6 Shift
Main Article: Level 6 Shift

After the defeat of Accelerator by the hands of Touma, the level 6 shift experiments involving the 20,000 sisters had finally ended. As a result, Amai Ao - investor and director of the experiment - is heavily indebted after the failure of the project and installs a virus into the 20001st sister Last Order. As part of a self-defense program, Last Order breaks out of her incubation chamber in order to seek the help of Accelerator.

Yamisaka Ouma
Main Article: Yamisaka Ouma

At an undetermined time prior to the beginning of the arc, Yamisaka Ouma had met a girl in the hospital whom had cursed markings over her body. Mistaking him for a funeral worker, the girl had several conversations with Ouma who had begun to realize that this girl was cursed to die and that she had accepted her inevitable fate. Over a period of time, Ouma began to fall in love with the cursed girl and seeked to save her life through magical means. On August 31st, he enters Academy city in hopes of extracting a grimoire from Index that will presumably save the life of the woman he loves.