PLEASE HELP ME FIND THIS MANGA

i read this one school life shoujo manga a long time ago and all i can remember is that the girl was caught smoking on the terrace by the guy and she was adopted and he has a kid and there was this one scene where she can't remember her real birthday so he lets her share the same date of birth as his kid and gives her a shoulder ride or sumn i can't remember the name so if anyone has read it please tell me what it was PLEASE