On the day Tōma Kamijō and Index see Academy City's space elevator, Endymion in the distance, they meet a Level 0 girl with an amazing singing voice, Arisa Meigo. As the three enjoy their time together after school, magic-user Stiyl Magnus suddenly attacks them. His target: Arisa. Why would a girl from the science side be targeted by someone from the magic side, Tōma wonders. In the chaos of Stiyl's attack, he tells Tōma, Index and Arisa that she might cause a war between the magic side and the science side.

Bonus animation featuring Index-tan included with the BD special edition of the Toaru Majutsu no Index: Endymion no Kiseki movie.

In Toaru Kagaku no Railgun T Mikoto Misaka and her friends prepare for the Daihasei Festival, a seven-day sports competition between different Esper schools, which, of course, also include the Tokiwadai middle school. Misaka and all other students of Tokiwadai are highly motivated and ready to do their best in the upcoming competition. However, all the fun ends, when another dark secret of the Academy City of Science and Technology is uncovered.