Chuuya, when he goes outside the wall to get medical supplies, finds his boyfriend, who is clearly a zombie now. Zombies are very aggressive creatures. They do not feel pain, fear, fatigue; their higher brain activity does not work, they do not remember who they were and generally there is no memory of life before their conversion. They are guided only by primitive instincts: hunger, motor movement, aggressiveness towards healthy subjects and their murder.