Toaru Kagaku no Railgun SS3  

At Tokiwadai, during a peaceful afternoon, Kuroko tries to relax after a tiring day when Yuri Sakibasu from Black Twintailed Yuri Sakibasu causes her some trouble. When Mikoto hears about it, she suspects that Sakibasu was sent by Shokuhou's group as part of their harassment war. As a result, they decide to take on the challenge of a violin competition against Sakibasu and his Stativarius violin, which costs more than 100 million yen. In order to defeat money with knowledge, they enlist Uiharu and Saten's help in figuring out the secrets of the Stativarius violin's sound and the subtle differences between it and other violins. During this intense enemy observation, they discover Sakibasu's impressive skills. However, this small conflict over violins is just the beginning of a much larger incident involving various desires.

Toaru Kagaku no Railgun SS3 was included with the limited-edition Blu-Ray/DVD volumes of Toaru Majutsu no Index III.