https://www.youtube.com/watch?v=qzY3EaJTuJk /covertly trying to spread the show whenever possible/

https://www.youtube.com/watch?v=6zEh3LpFbY8 - From The Devil is a Part-Timer. I remember either an ending or OP that I really liked, too, but that was at least in part due to the animation sequence associated with it and I'd have to look harder to find it.

And I think this OP has a fair amount of recognition among watchers, but Showa Genroku Rakugo Shinju itself doesn't have a very wide audience -- or I would guess it doesn't, based on the topic of the show -- so https://www.youtube.com/watch?v=K28Lcc-MdJs.

Dunno if they're underrated (probably not) but I've always loved these two, in full:

https://www.youtube.com/watch?v=7kvmPh2nYBM
Journey

https://www.youtube.com/watch?v=XmqRsIudBII
Zankyou No Terror

lol, people need to watch the anime. There's no way you can't fall in love with the ost.

Ikr ? not many people seem to know about it though

lol, I was planning on coming to this thread to post that song. parasyte ost so good.

Slowbro

i like no more heroes'

https://www.youtube.com/watch?v=e73EDBGrHQg
this?

i like no more heroes'