If you're looking for manga similar to A Certain Magical Index, you might like these titles.
A hero who manages world peace. There were twins who longed for their overwhelming power and vowed to “become a 'hero.'" However, a few years later, his younger brother, Yosai, broke his dream and became a cleaning worker to clean up the heroes. Yosai tells herself that she has a position (rank) that was decided by nature, with her brother who became a hero sideways. However, when I saw the despair of my important childhood friend, the dolphin, I was prepared to go against that fate with the first and last resolutions!
This is a world where humanity is always at war with the Unknown. The kids who were evacuated to a cold sleep facility during the initial invasion decades ago wake up from their slumber to find that they'd manifested superpowers called the "World." To protect Japan from the Unknowns appearing from the Tokyo Bay, these kids would start their own battles at the defensive strongholds of Tokyo, Kanagawa, and Chiba.
Mysterious objects from space have landed, embedding themselves within human beings around the world and granting them impossible powers according to their deepest wishes. Seventeen-year-old Utsugi Minoru's only wish is to be able to live apart from the world and events around him. But will he remain the same after experiencing his new powers--and new dangers?
One day, Kamijou Touma faced yet another misfortune. His toilet was broken and spraying water everywhere. As he was lamenting his misfortune, suddenly he appeared in a strange place along with Index and Misaka. Soon enough, more strange people begin appearing...
In Academy City, there is a popular next-generation contest. In reality, this is a hand-to-hand battle between gigantic Virtuaroids that appear on the streets. It’s formally called as “Computerized War Machine Virtual-On”. Since it can be argued that Level 5s and Level 0s are equal given the technique, it has spread with explosive force among the students of Academy City. One day, Index with her white Bal Bados, fights Touma’s stock Temjin. “I’m Ririn. Purajina Ririn. I’m not Ririna… Munya…” A seemingly insomniac girl arrives at Academy City. And, Kamijou has an encounter. The usual Virtual-On meets an unavoidable unprecedented accident. That is, the Computerized War Machines fuse with Academy City, a sign of a grand battle about to happen! Misaka Mikoto and her Raiden, Shokuhou Misaki and her Angelan, as well as many others will make appearances!
Spring is here, and the graduating seniors of First High are planning a getaway to sunny Okinawa. At the same time, Tatsuya and Miyuki will be on the island as the Yotsuba family’s representatives at a memorial service for the victims of the invasion there several years earlier. Of course, this is just a cover for their true purpose: foiling a terrorist plot hatched by some deserters and Australian operatives. Their primary target is a party that Shizuku and Honoka will be attending—What are the chances?
Rengo Orii loves superheroes. Other people say that his favorite, Megalith, is an old man who should just retire already, but as far as he's concerned, anything Megalith does has to be true justice. One day, a bizarre encounter leaves Rengo with the power to transform... not into an awe-inspiring superhero, but a horrifying insectoid monster! Rengo realizes that even though he might not look the part, he can still be the superhero he's always dreamed of being now, but it turns out copying Megalith's signature knee to the face isn't such a good idea when you're strong enough to kick someone's head off! Can a monster with a little kid's sense of justice really be a hero!?
Siblings Ayane and Kurumi have unique super natural powers known as "Ghosts," each with their own unique score that designates their powers. Ayane has a score of "7," while Kurumi has a score of "11." Ayane's ability allows her to control shoe laces, while Kurumi can form contracts with objects, which allow her to control it. Ayane feels severely inferior to her sister, but will she be able to prove herself against the other "Ghost" bearers in combat?