We don't need to be technical about it, lol. It's a fictional roleplay, and most of our characters have not even met yet. It would be no different than getting PE class and not knowing anyone, and then winding up connecting with these people through that P.E. Class.
Just because it's INSPIRED by Japan doesn't mean we have to do everything like it's Japan. It's it own little school inside of Japan, or wherever the GM said it was and again, it's a fictional roleplay with anime characters. It would be fun to have everybody in the same P.E. class, and it could be that maybe some of the characters didn't take P.E. already or they want to take it again.
P.S. When I was in school there were freshmen, sophomors, juniors, and seniors because gyms are large enough to hold everyone and so is the track and field and where ever else we went. Our school had over 3,000 people lol, though there were only about 50-60 people in each class. I don't see how this makes a difference in a roleplay. I don't think the WHOLE school is going to be in the same period of PE, just our characters and obviously some NPCS.