Looking for yaoi manga (?)

i only remember bits: a highschool boy is crushing on a fellow student. highschool boy sits by the window of his class, and his crush in the next room sits by the window, too. and he used to stare at his crush all the time until his crush noticed him and started talking to him using paper and pen.

i'm not sure if it's a manga, but it's was drawn in just black and white so...

that's all i really remember from a facebook post i saw before.

i hope someone can help