Does "Requiem of the Goddess" add any more to the story?

I'm planning on finally playing Lighting Returns - Final Fantasy XIII but before I did I thought to refresh my memory of the ends of the previous 2 games. When I went to play XIII-2 I remembered I never did buy the Requiem of the Goddess DLC.

After beating the final bosses again I tried it out, after loosing a couple of times I defeated Caius at Level 2 (3 stared) however then I was taken back to the pre-battle screen and when I went to go into battle I fought Caius again.

I am wondering, does the Requiem of the Goddess DLC add any more to the story (i.e. how Lighting went into Crystal Stasis and why Caius believed he killed her) or is it just endless figthing and grinding Caius until I can 5 star him?