Board Thread:General Discussion/@comment-24319911-20160701130131/@comment-173.68.249.142-20170727214232

Blast is saitima. In the beginning of the anime, remember that saitima saved a kid from the crab man, well that kid was the grandson of the creator of the hero association. So when the creator heard about it, he made up a hero named blast and made him class-s rank 1 for saving his grandson.