mc is in love with childhood nice sensei meets again as high school sensei and he's now rude, its really the childhood sensei's twin.
mc's male friend has a crush on him but gets with their female friend.
child sensei is together with another teacher, they get married.
follows them through the years and they get together at the end, has a sequel follows the mc's friends' kids.

________________
Smiles Conceal Knives - Lynn Flewelling.
There is No Such Thing as BAD Words.