Jang Hwa-bin who had Polycythemia was once bitten by an unknown creature out of no reason. Never did he expect that his new desk mate from the new school would be the very one who bit him. It turns out that person is a bat that travels every night for food-hunting. To keep the bat from hurting more people, Jang Hwa-bin decided to keep him and feed him on his own. How would their stories unfold after that?