Zenchiteki na Dokusha no Shiten kara (Anime) Wiki

Back then, Dokja had no idea. He had no idea his favorite web novel, ‘Three Ways to Survive the Apocalypse,’ would come to life, and he would become the only person who knew how the world would end. He also had no idea he would end up becoming the protagonist of this novel-turned-reality. Now, Dokja will go on a journey to change the course of the story and save humankind once and for all.

Source: Webtoon