Twelve years ago, as the U-20 virus spread around the world, the whole world was in an uproar. However, due to the appearance of zombies infected with the virus, Hee-won is bitten instead by zombies that were running towards Woo-jun, and symptoms of fever and hives begin to appear... "I'm scared, Woo-jun. Can you please kill me?" "How can I do that, to someone so kind-hearted..." Woo-jun is shocked to see Hee-won disappear rights in front of hi eyes with a loud explosion. A few years later, Hee-won, whom he thought was dead, appears in front of him in the same appearance, confusing Woo-jun... "Who are you?" "I am Chae Hee-won, the guide that is in charge of Captain Kang Woo-jun this time".