My Sister Can't Be That Zombie

Si Lang and his sister Yimei both became immortal ghosts due to a car accident in middle school. In order to experience the feeling of human love, the ghost Yimei possessed a beautiful girl and went on a date. At this time, the Ebola virus and the dengue virus mutated in the mosquito's body. Due to the girl's zombie transformation, Yimei cannot leave the girl's body. In order to save Yimei from the girl's body, Si Lang and Yimei searched everywhere for a vaccine against the biochemical virus. The twin sisters holding spears, and the short-haired lolita holding an ill-fitting sword. The way to defeat zombies is actually zombies? Why does the ghost Si Lang carry a sword on his back? Where will the boys and girls go?