i think you guys are forgetting one important detail to the 5 "main characters" ... they are supposed to be the names that YOU named them as a character as they are supposed to represent YOU. so the OP can name them anything they want in their fanfic lol..

for example i made a Lightning Main thinking i couldn't change it (when i first started) so i named him Hayase.. Yondaime Hayase because in my fanfic Hayase becomes the fourth hokage instead of minato (made up name obvs).