Both an incredible manhwa and light novel. Based on the LN of the same name omniscient reader is one of the best reads of the modern era. I truly recommend to anybody who is interested in fantasy even though it is not particularly over the top. I think explaining the plotline only hinders at your enjoyment so i suggest going in blind. Give it 5 manhwa chapters and if you're not hooked its not for you.

Brief Synopsis: Our protagonist is an average salary man who loves his light novels. During his childhood he follows a certain one for an extended period over multiple years until current day. After work on the day of the final chapter release he is met with a sudden change; the world has descended into chaos only its a very familiar one.