Legacy: Heroes Beyond the Shell

Heroes Beyond the Shell is a TMNT 2012 x My Hero Academia crossover where the Turtles, April, Casey, Karai, Shinigami, and Rahzar are thrown into the MHA universe right before Izuku Midoriya's life starts changing forever. What begins as a portal accident after the end of TMNT 2012 Season 5 Episode 9 quickly turns into a full-blown collision of worlds, with the mutant ninja team landing in front of Aldera just in time to get dragged into the sludge villain incident alongside Izuku and All Might.

From there, the story snowballs into something huge. Izuku receives One For All, but it mutates in a shocking new direction, unlocking the ability to permanently copy quirks, upgrade them, remove their drawbacks, and even transfer those powers to other people. That one twist changes everything. Rahzar is restored back into Chris Bradford while keeping full control over his wolf form as the hero WolfSlash. Timothy "The Pulverizer" is saved from Mutagen Man and reborn as a hero with the transformation Glacier Gator, a devastating water-and-ice powerhouse. Toga is redeemed. Koro bonds to Izuku. Yatsufusa turns five defeated Nomus into loyal upgraded puppets stored in his morpher. And one by one, powerful Teigu from Akame ga Kill permanently fuse with the TMNT cast, giving Raphael, Michelangelo, Donatello, Leonardo, April, and Casey deadly new armor, elemental weapons, constructs, and vehicles.

The story blends heart, comedy, spectacle, and over-the-top action. Izuku and the TMNT crew train on the beach with All Might and Gran Torino, build a chaotic but loyal found family, survive the USJ attack, and storm their way through the Sports Festival with upgraded quirks, new forms, giant summons, and absolutely zero subtlety. The cavalry battle becomes a war zone. The tournament matches hit hard. And through it all, the characters stay true to themselves while adapting to a world where heroism is both public performance and personal choice.