fly. When he notices Tadashi and Ms. Yoshiyama interacting, he attacks them both and captures her. In the OVA version, Koyanagi is shown as an antagonist who went insane and connected an infected Tadashi to the custom Walker. : Assistant of Doctor Koyanagi, who cares for him and Tadashi. When she was seen with Tadashi by Kaori, Kaori tried to attack her. Ms. Yoshiyama then ran outside where she was captured by the Mechanical Koyanagi. She does not appear in the OVA adaptation. The Citrous Circus: A circus troupe who establish themselves in Tokyo following the growing death stench pandemic. While most of the troupe and its animals have been infected by the disease, the seemingly immune ringmaster uses the infected and their walking machines to perform acrobatic shows, and appears to have gone insane as a result of learning of the Death Stench's true nature. Shortly after Koyanagi's flying machine is activated, the Citrous Circus attempts to use a cannon to bring down the machine, but to no avail. The Students: A group of biology students from Kyoto University, who are immune to the Death Stench disease. Introduced at the very end of the story, Tadashi met them after the Citrous Circus attempted to attack Doctor Koyanagi's flying machine. After explaining their immunity, it is revealed by the group that the virus responsible for the Death Stench is constructing walking machines from iron-rich shipwrecks, and that they are researching a vaccine that could be capable of stopping the growing pandemic. Tadashi chooses to join the students following this discovery. : A freelance videographer, appears only in the OVA adaption, Kaori met him in the airplane to Tokyo. Follows Kaori just to get to the location of doctor Koyanagi to get his research data. Got infected at the end of the anime before sending Kaori away to a group of survivors. : Friend of Kaori, appears only in the OVA adaption. She is meek and slightly overweight and feels unattractive, appears to be bullied by Erika. Turned into a walker at the end of the anime. : Friend of Kaori, appears only in the OVA adaption, an outgoing and attractive girl who has no difficulty attracting other men, and appears to be picking on Aki all the time. She gets infected by the walking fish early on. During a fight, Aki bludgeoned her to death with an ashtray, but she