Yū Kodama survives the zombie pandemic barricaded inside Tokyu Kabukicho Tower alongside five others: Ranna, Lili, Fumika, Murumuru, and Rumina. When Mikoto Amano and an unidentified man are discovered and brought into their refuge, Yū becomes entangled in the murder investigation after the man’s death. She actively joins group discussions where suspicions emerge and evidence is examined, including a potential murder weapon uncovered in another girl’s possessions. During a zombie breach that compromises their defenses, Yū fights off the attackers and later aids in the search for the missing Rumina. As tensions mount, she participates in decisive group votes, such as determining a bitten survivor’s fate, and contributes to alibi revelations where secrets surface among the survivors. Throughout these crises, Yū remains engaged in the collective struggle to identify the murderer while confronting threats from both internal discord and relentless zombie assaults.