As we all wait to see if this series will get a simulcast pickup, a new teaser has landed in Japan for the April 12th debut of A Certain Scientific Railgun S. The sequel season to the series has its short form TV commercial with narration by Sataomi Arai for it, as the promo deals with the character she plays in Kuroko Shirai.
Plot Concept: The second season will focus on The Sisters Arc. Lasting only a single volume in the Toaru Majutsu no Index light novels, it was later expanded greatly in the Toaru Kagaku no Railgun manga.
The arc focuses on the ordeals of Mikoto Misaka after discovering the existence of the Radio Noise sisters that are being used in the Level 6 Shift, an experiment where they are killed in order for the highest-ranking Level 5, Accelerator, can achieve Level 6.
[Source: ANN]