Board Thread:General Discussion/@comment-4435241-20170331114416/@comment-11860859-20170411163827

Yeah, Kira Hiroto in the original series was older than Hitomiko-if he kept living in that timeline he would have been in his 20's. They made him younger in Ares so he could be part of Eisei Gakuen. Same with Atsuya-changed them from twins to Atsuya being a year younger than Shirou so there could be the Senpai-Kouhai relationship.