It's been a long time since the zombie apocalypse begun in the city. Rui and Tsukasa are the only alive human. And also, they are a couple helping each other survive in such a difficult time. Once, while running away and fighting off another flock of zombies, Rui noticed how one of them attacked Tsukasa. But still, having managed to fight back, they ran into cover, where they were able to take a break. But when Tsukasa rubbed his shoulder with his palm, he noticed traces of blood from the bite.