In Toaru Kagaku no Railgun S, Mikoto Misaka and her comrades delve into rumors circulating throughout Academy City. Unveiling a chilling truth, Mikoto stumbles upon a series of ghastly experiments targeting thousands of espers—clones of herself. Driven by guilt, she embarks on a mission to halt these atrocities. Yet, the adversaries she faces exceed her expectations, pitting her against formidable espers. As she grapples with the grim reality of her involvement in the experiments, Mikoto plunges into a harrowing battle for justice. Amidst the turmoil, Academy City's pulse quickens, offering a turbulent saga where moments of solace are scarce and challenges abound.