Kotetsu is a veteran hero who dedicates his life to using his NEXT powers to protect the people of Sternbild City. Previously the King of Heroes, Kotetsu had started to decline in the competitive Hero TV show, and as a result, his sponsor company was bought out by Apollon Media. Shortly afterward, he is forced by his new sponsor to form the world's first hero team with Barnaby Brooks Jr.
Kotetsu is a also a single father who struggles to balance his job as a hero and his daughter, Kaede.