I’ll Retire After Saving the World is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Year 2044. Right before the global explosion of dungeons—the end of the world. And… when I opened my eyes again, it was twenty years before the end. I, Woo Hwijae, must stop the apocalypse to secure my retirement plan!