songs that are unofficial theme songs for a character/ship

what is a song you associate SO MUCH with a character/ship that verytime you listen to it, it reminds you of them?
eg.
mr. loverman – ashx eiji (banana fish)
and ofCOURSE this part is for gojo x geto (jjk)
"the ways in which you talk to me"–SUGURU
"have me wishing i were gone"–SATORU

copines – han seojum (true beauty)