A Certain Magical Index, manga Vol. 11

Kuroko Shirai is embroiled in a case that involves her beloved "big sister," Mikoto Misaka. As Kuroko squares off against a fellow teleporter for the remains of the orbital supercomputer known as the Tree Diagram, the effects of their battle reach far and wide--affecting Mikoto, Touma, the worldwide network of Misaka clones...and even Academy City's strongest esper, Accelerator!