The Days When I Was Studying and Cultivating Immortality in Another World

Ren Feng always thought that cultivating immortals was a story in mythology, but it wasn't until he traveled to another world that he discovered that it really was possible. Don't take off directly this time! Faced with all kinds of strange beasts and killed them directly, why are there aliens? What to do if there is no system? It doesn't matter, I can cultivate immortality.