Are anime OP/ED theme songs original?


Are anime OP/ED theme songs original? Is it like after creating an anime, the
producer hires a singer to sing a song for the OP/ED theme for that anime, or
do they just use songs that the singer already sang for his album or something
like that?




The vast majority of the time (easily upwards of 95% of the time, by my
estimate), OPs/EDs are produced specifically for the anime they're used in.
Reuse of existing songs is rare.

There are counterexamples, though, which by their very rarity prove the rule.
A few select examples:

  * _Erased_ reused Asian Kung Fu Generation's 2004 song "Re:Re".
  * _JoJo's Bizarre Adventure_ (2012 version) reused [Yes](https://en.wikipedia.org/wiki/Yes_\(band\))'s 1968 song "Roundabout".
  * _Speed Grapher_ reused Duran Duran's 1981 song "Girls on Film". ([Thanks, @ConMan.](https://anime.stackexchange.com/questions/31790/are-anime-op-ed-theme-songs-original/31792#comment44253_31792))
  * _One Week Friends_ reused Sukima Switch's 2004 song "Kanade", though in this case, it was re-recorded with Amamiya Sora (voice actor of the character Fujimiya Kaori) as the vocalist.
  * And, of course, _Neon Genesis Evangelion_ uses [a great many different recordings and mixes](http://vgmdb.net/album/19791) of the classic "Fly Me to the Moon" as its ending theme. 




The vast majority of the time (easily upwards of 95% of the time, by my
estimate), OPs/EDs are produced specifically for the anime they're used in.
Reuse of existing songs is rare.

There are counterexamples, though, which by their very rarity prove the rule.
A few select examples:

  * _Erased_ reused Asian Kung Fu Generation's 2004 song "Re:Re".
  * _JoJo's Bizarre Adventure_ (2012 version) reused [Yes](https://en.wikipedia.org/wiki/Yes_\(band\))'s 1968 song "Roundabout".
  * _Speed Grapher_ reused Duran Duran's 1981 song "Girls on Film". ([Thanks, @ConMan.](https://anime.stackexchange.com/questions/31790/are-anime-op-ed-theme-songs-original/31792#comment44253_31792))
  * _One Week Friends_ reused Sukima Switch's 2004 song "Kanade", though in this case, it was re-recorded with Amamiya Sora (voice actor of the character Fujimiya Kaori) as the vocalist.
  * And, of course, _Neon Genesis Evangelion_ uses [a great many different recordings and mixes](http://vgmdb.net/album/19791) of the classic "Fly Me to the Moon" as its ending theme. 

