Thread:Minitrue11/@comment-6429245-20170908180054/@comment-33040357-20170909025905

Actually, in the first episode, there was a part which showed Yume and Koharu in their old school, and the Japanese school year typically lasts from early April to December 25. So I'm guessing that the scenes where they visited the S4 concert and where they are in their old school takes place at about November 2015, when Hime was still 14 (maybe), and then it skips a few months (includes February) where they already are in Yotsuboshi Academy and that's when Hime is already 15 (maybe). Though in reality there's no real way of knowing their age since the creators didn't give them out... yet. In real life you can be in the same classroom as someone younger or older than you by a year or two.