I have forgotten the name of this shoujo or josei manga that is about a female teacher who had a student who had a huge crush on her during her teaching training days, but when he confessed to her she rejected him. This guy then decided to be a teacher as well and he ended up at her school that she is teaching as a teacher in training himself. Uh. this is as far as I can remember. not sure if it has smut or not. And i thiiiiink it's a one shot? In any case it shouldn't be longer than one volume. I hope that info is enough to jolt anyone's memory. It's been bothering me for a while that I can't remember the name for it. Thanks!!
I know it's not the story you are referring to but it kind of reminds me of Ningyo ga Fuchi, it is the girl student being in love with her sensei and then becoming a teacher herself. So I recommend it to you