Izuku Midoriya is a superhero and the main protagonist of the manga series My Hero Academia, created by Kōhei Horikoshi. In the series, he is a nerdy and ambitious high schooler misfit and the 9th (and current) holder of "One For All" (ワン・フォー・オール, Wan Fō Ōru), a superpower which combines eight different individual superpowers, or "Quirks", together and creates powerful bursts of energy, and also has the unique ability to be passed off to other people. Initially born without a "quirk" to call his own, Izuku nevertheless grew up with aspirations to become a superhero in his own right. Nicknamed "Deku" by childhood classmate and middle school bully - Katsuki Bakugo, Izuku would later save him from a villain, in turn winning over the interest of All Might, Izuku's childhood idol and #1 hero, who in turn passes down his sacred One For All quirk to him. After being accepted into U.A. High School, Izuku's classmate Ochaco Uraraka inspires him to embrace his nickname and use it as his hero name.
I think Izuku would be a good campaign candidate for world ruler because he suffered through the way society treated disabled folks and people who are not as fortunate to have powers, influence or money, while also having amother who taught him to be kind and empathetic to others. Due to this, he is especially well-equipped with an understanding on how his society has failed him and what needs to be changed. Throughout his journey of getting immense power and privilege practically overnight, he is also met with other people-- often "villains"--- who were also wrongfully mistreated and thus became villainous as a result of that. He is an incredibly caring individual and with this understanding on how the peopel in his world are effected by society, he would strive to make better changes for the people around him so it wouldn't happen again.
I think Shouto would be a really good running mate not just because he's from the same universe, but also because he's expereinced a different level of privledge and turmoil due to the way his society is structured. He expereinced privilege in the basic sense, but he understands how that sense of privilege twists people into enacting cruelty and mass harm onto the society as a hole. From this expereince he has an even more special understanding on how his society needs to be changed to make sure more kids aren't subjected to the torture he had experienced.
The top campaign platform would be the universe of My Hero Academia and over Twitter, because it's a very well-understood social media and is a canonical occurence in the universe..