a little lighter than the others on this list but the two main characters are truly devoted to one another so i think it still counts :)
16 days
What can a LIST do?
You may feel your favorite manga should be gathered together into distinct categories for your own reference and, now, you can do this with a LIST. After you've created your list or lists, you can proudly recommend them to other manga fans to showcase and share your taste in manga.
My Six Days With Eve