In Shuumatsu no Harem Episode 5, titled "First Victim," Reito Mizuhara's quest to understand the origins of the MK Virus leads him to Keimon City, the virus's initial outbreak location. Accompanied by his new attendant, Rea Katagiri, and virologist Maria Kuroda, Reito visits the hospitalized widow of the virus's first victim, seeking crucial information. However, their investigation faces challenges as the widow is initially uncooperative and later becomes critically ill due to a mysterious poisoning. Amidst these events, Reito's interactions with his companions grow more complex, especially following an encounter with an American named Chloe, who attempts to seduce him, leading to tensions within the group. This episode deepens the series' intrigue by blending elements of mystery, interpersonal drama, and the overarching theme of survival in a post-apocalyptic world. The introduction of new characters and the evolving dynamics among them add layers to the narrative, keeping viewers engaged as Reito navigates the challenges of his mission.