Touma walks into another war he didn't ask for, swinging his negation fist at problems that require diplomacy. The show knows it has to prove it learned from season one's mess, and it does, arcs land with actual weight now, the pacing breathes, and Misaka gets scenes that remind you why people care about her beyond the tsundere bit. Index II builds a world where science and magic are two sides of the same broken system, and watching kids try to survive it becomes genuinely tense because the stakes stop resetting.

Index is still on the run, and powerful magical organizations and individuals are after her for the books stored in her memory, even if taking them costs her life. She can count on Touma, who has always stood between her and danger, along with Misaka and other friends from Academy City. As friction between the world of magic and Academy City grows, Touma uses his power of negation against both espers and magicians to keep the people around him safe, with old and new allies and enemies joining the fight. One crisis involves a stolen grimoire and a kidnapped nun, Orsola Aquinas, who may know how to decipher it. Another unfolds during the Daihaseisai sports festival, where a weapon said to kill Saints with a single blow changes hands. A wider war between magic and science looms.