It doesn't matter if the male protagonist is not a human being, and neither is the female protagonist. What? You said it's okay for the male supporting actor to be a human being, oh no, no, no, no one who appears frequently in this is a human being.
Taking place in the early Republic of China, the first meeting that the male protagonist thought was just the first meeting after hundreds of years.
The heroine is a female ghost from the Song Dynasty, and she has lost more than half of her memory.