after mamoru and jadeite graduated from moto azabu high school, zoisite transferred to juban public high school. mamoru and jadeite were the only students at mahs that zoisite liked, and while it was very prestigious, if a public school is good enough for ami (who is way smarter than everyone ever) then it is good enough for zoisite. plus, most of the senshi attend school there, zoisite likes (or at the very least tolerates) them, so why not spend his last year of high school with people he doesn’t mind being around.
he and jadeite were the best fencers in the school at mahs, so zoisite joins the fencing club at jphs and shines there, as well as with academics and chess (though ami always beats him there). he was actually looking forward to his last year until the three lights showed up. then zoisite spends his last year both eternally annoyed at everyone, and protective of usagi because fuck off, seiya.