Develop a Protagonist to Live in Doomsday

The apocalypse is coming, the arrogant sister does not come home, the gangster brother lives with the rich woman, and there is only a dog by his side. How can the apocalypse come so easily? Fortunately, thanks to the Skyfall System, time goes back to before the end, and now he can save the world (?) By sending his pen pal to the top! Write letters to become a medieval girl, a vampire boss, a little prairie prince... Our goal is to make it easier to be gay! "My dear, I only said that I want to build a base. Can you not teleport the castle here?" This article is also known as "The Man Behind the Protagonist", "How Can My Pen Pal Be So Cute", "I Didn't Expect You to Be Such a Protagonist" and "Can You Call Me, Please Don't Call Me or Please Don't Call Me at Such a Dangerous Time"