Great thread, but i think your underestimating Minatos age at time of death, and overestimating Hirzuens age at the time he became Hokage. I cant remember the page chapter, but there is a flashback of the founding of Konoha in which Hiruzen looks really young when trained by Hashirama and Tobirama. By this timeline he would have been twelve and he looked 7-8 max. For Minato, we know he died before 30, but to say he was 21 is too young. I would guess 25-26, i know he was a genius but I dont think he was that powerful at only 21.