Angel

Angels are immortal entities (just like ghosts) that were once found only in mythologies, but ever since they were brought into real world (evolution world), sapient species that die will become angels and live forever. Unlike in mythologies, angels aren't restricted to heaven, as there's no heaven nor hell in real life Earth, so they remain on Earth. Also unlike in many myths, angels can be seen, heard, smelled, touched, etc by all kinds of life on Earth. They are distinguished for their immortal lifespan and large bird-like wings (with feather-like structures) for flight. Since they're immortal, they can't die from any death causes, so they don't need to feed, drink, sleep, etc.