I am 95% certain the mc went back in time but all i can remember from the series is the mc is among other people inside a kind of magical library where the librarian is a small boy and they have to pick 3 of his books and make them reach a conclusion that the librarian will enjoy,
The thing is a lot of those books represented a sort of apocalypse or just the end of the world it shows
And the mc could see status windows of people so he could tell what novels they'd be good with
. I can't remember anything else from this series other that that event unfortunately,
i hope it's ok to ask for a webtoon since everyone's only asking about manga...
PLEASE the cute yet cruel floating librarian is living rent free in my head and he won't leave T^T
The story was originally korean but i read it in eng probably last year

I'm pretty certain that's SSS-Class Revival Hunter

That is exactly it, thank you
I can't even remember why i stopped reading