a short and sad anime??

so tittle says it all. i want to watch an anime thats depressing or more like the ending is. it can be romance or from any other genre. all i want is something that makes me so sad i cry or atleast its heart wrenching. but also it should be short can be a movie, i dont fw movies much nowadays tho. but the max episodes should be 15 or few. i got exams too so i want to finish it in one day or so.