Trying to find the name of a shoujo/romance manga I read a while ago --

I specifically remember a girl who ends up reconnecting with a childhood friend/crush(?) by accident. They were in a club for track or long/short distance running when they were younger - I think the girl was tom-boyish and had short hair when she was young. When they're older, maybe high school, they happen to stand next to each other on a bus or train, holding on to the rail above. He has black hair and has headphones in, her hair is longer and she looks prettier/older, and I think they recognize each other but don't acknowledge each other at first.

Later on in the manga he is on a run and bumps into her while she is walking somewhere, they talk about how she quit running when she went to high school, and in the past never took the club seriously / she looked up to him when they were younger. He's not a main character - at least not at first - I believe she was already interested in or is dating someone else at the beginning of the manga and this childhood crush appears on the side a few times throughout. When I read it I don't believe there were many chapters, so I don't know if he becomes a more significant character.

Can't remember the name at all! Please help!