Toaru Kagaku no Railgun SS: Dasoku, Mata wa Toaru Jiken no Shuusoku
とある科学の超電磁砲SS 蛇足、またはとある事件の終息
This supplementary story serves as a conclusion to the events of the Railgun PSP game and was originally released in the PSP Toaru Kagaku no Railgun: The Complete Visual Guide.