The children of Deku and Ochaco would be interesting main characters. They could inherit a combination of their parents' quirks and personalities. For example, their child might have Deku's super strength but Ochaco's bubbly and friendly nature.
The main characters could also be students who are not related to the current heroes but are inspired by them. They could come from different backgrounds, like a student from a family of villains who wants to break free and become a hero. Or a character who has a very weak quirk but has an unwavering determination to prove that they can be a great hero, just like their idols from the previous generation.
Perhaps a story where the next generation has to deal with a public that is growing distrustful of heroes again, like in the early days of hero society in the original series. They'd have to work hard to regain the public's trust while also fighting villains.
Well, obviously Mandalay herself is a main character. Then there could be her fellow heroes like Tiger. Students she mentors might also be main characters, like Kota who she has a connection to in the original story.
It could be a new student at U.A. High School. Maybe someone who was a hardcore gamer in their previous life and now has to adapt their gaming skills to the hero world. They would have unique ways of approaching hero training and battles.
Izuku Midoriya is one of the main characters. He is the protagonist with the quirk 'One For All'. Bakugo Katsuki is also important, being Izuku's childhood friend and rival. Ochaco Uraraka, a female character with the quirk 'Zero Gravity', is among the main characters as well.
Uraraka could be an interesting side character too. Her friendly and upbeat personality could bring some light - heartedness to a story that might otherwise be quite serious when focused on Tsukauchi's detective work.
It could be Deku's successor. Maybe someone who idolizes Deku and has a similar quirk but with some new twists. They would carry on Deku's legacy and face new challenges in the future.
Sometimes, it might also feature well - known characters from the original 'Boku no Hero Academia' but with a psionic twist. For example, Deku could potentially develop some psionic abilities in addition to his One For All quirk, which would completely change his character dynamic and how he interacts with others in the story.
Izuku Midoriya is one of the main characters. He is a quirkless boy who dreams of becoming a hero and eventually inherits One For All. Bakugo Katsuki is also a main character, a powerful and often hot - tempered student. Ochaco Uraraka, with her zero - gravity quirk, is another important character.
Well, it could be new characters created specifically for the fanfic, who possess the so - called 'illegal' quirks. They might be young individuals trying to find their place in a world that doesn't accept them at first.