Hmm there are a lot or at least not only one or two for me, but doesn't really make me cry. For example, Acchi Muite by Swimy. Although it doesn't have a sad melodies,t when I thought about the correlation between the lyrics, melody, and story, it makes me sad. Nandemonaiya by Radwimps also has a sad impression on me. The lyrics are beautiful. This soundtrack makes me depressed and sad...
For me it would be i think "Secret base" i always remember the anime with this song Oh! And also maybe the song "if i die young" just a little tho My sad song list isn't wide