Hi guys. I couldn't remember the exact plot of this novel but the female protagonist awaken in a post apocalyptic world, met a superhuman man while being held captive. It has hundreds of chapter as far as i could remember. There's also a part where she was sent to a mission to an abandoned city, in a library to get something, and met spirits there. I think it's a reverse harem and the females are considered really important. Thank You!! Lmao i actually find it. HAHAHHAHA