
The story in the present is already the 3rd timeline.
In first timeline, J turned back the time using his watch that was given by the system (the one he tried to trade in chap 1 for food with grandma).
In the 2nd timeline, some of J's power was still in the watch. So when J, died (Sayoung was holding J's cold and dead body), Sayoung used the watch again to turn back time with the help of the S ranked highschool kid, and the artisan (because he wanted J to be alive again, not save the world from the apocalypse since it's inevitable to happen).
And finally, this is the last chance. They still don't remember the 2nd timeline but when they did, the 2nd timeline and 3rd started to merge. So now, in the novel they're fighting with monsters and Prometheus because the apocalypse came so early because of the group that's distributing drugs.
*The more the people say "the end is near" the more it will happen soon. This is what the 2nd timeline Sayoung said to J, when they met.

I love the twist. I love how Luca and Judith both realized their mistakes in the past and didn't actually hate each other. I love how they opened up to each other and trusted even Rudiger to tell their story. I love so much how they mended their relationship! A mature manhwa with family genre and romance without too much cliche! (Rudiger's such a golden retriever! From cold hearted man to a cry baby for Judith)
Wahhhhhhhhhh the cling hanger