I remember it was about a popular girl who is a tomboy and her personality made a lot of girls fall in love with her and the guy is also popular for his look (and grades?) they both are best friends and the whole school knows them, and so the girl's sister (i think they r not blood-related) joins the school and she is very protective of her. Also in the school, there's a gang who try to bully or torment the girl and guy because they are popular (the gang's leader was a teacher they both knew) and towards the end, they both realize they love each other and you know the regular happy ending. This is DEFINITELY a manga but I can't remember the name of it also the manga took place in a high school.
(Sorry if there is too much info, I wanted to be as detailed as possible to make it a bit easier to think.)
