Interesting question with a complicated answer!
So my comic, Niji Chikara, was originally meant to be an animated series. Because of that, I wanted to make an anime opening for it, and ended up latching onto a song from DDR called Nijiiro. I considered this Niji Chikara's unofficial theme song.
...But obviously I wasn't going to actually use that song for the actual anime opening, so what I ended up doing was writing a song with a similar structure called Color of Chikara, which now is Niji Chikara's actual theme song. I haven't posted the full song anywhere yet (nor the accompanying anime opening), but I included a piano version of it in the medley used for this speed draw:
(The other songs in the medley are other songs I originally made for the animated series!)
...But none of that says much about the comic itself, so uhhh the song I usually cite is Superman by Five For Fighting, if just because it's the only song I know of that talks about the struggles of being a superhero while also struggling with being human.
...And if that textwall was interesting to you, check out my comic lol