A Certain Magical Index NT Novel Volume 4 was written by Kazuma Kamachi with illustrations by Kiyotaka Haimura.

In the fallout of the attack on Hawaii, the twenty-seven partner corporations that broke away from Academy City announce that they will be hosting “Natural Selector,” a combat tournament in Eastern Europe. By holding the event, the Anti-Academy City faction hopes to prove the existence of powers that surpass psychic abilities, thereby destroying the identity of Academy City. With the help of Gremlin, an organization that merges magic and science, their scheme gets underway. Will Academy City be able to stop them before it's too late?