ship carrying the prototypes for the walking machines. A short while later, Tadashi returns to find Koyanagi missing an arm. As he was examining the machine in detail, it used a series of spikes and tubes to latch on to his arm, forcing him to amputate it. The walking machine scuttles into the room, now carrying Koyanagi's arm instead of the fish. Soon, Kaori and Tadashi discover that hordes of marine life with legs are in the process of overrunning Tokyo, having gradually invaded the Kantō region. Infected by the gas, Kaori becomes depressed by being subjected to her illness's symptoms, and attempts to commit suicide. Tadashi takes her to Koyanagi in an effort to save her but falls into a canal where he passes out after being injured by thousands of small walking fish. Awakening a month later, he discovers that Koyanagi has placed her into a custom-built walking machine. Upon switching the machine on, Koyanagi is mortally wounded by Kaori, who quickly escapes. Wandering through the desolate city streets, Tadashi finds that most of the walking fish have decayed, and that the walking machines are now carrying infected citizens instead. He then encounters a circus, where he learns from the ringmaster that the gas appears to be alive, taking on a soul-like appearance when ignited. Tadashi encounters Kaori and retrieves her from one of the acts at the circus. As the pair arrive at Koyanagi's lab, Koyanagi's assistant, Ms. Yoshiyama, reveals that the doctor died from his wounds. When she attempts to remove the walking machine from Kaori, Koyanagi appears, now mutated by the infection and attached to a modified walking machine in the form of an airship that allows him to fly. Kaori notices Tadashi and Ms. Yoshiyama together and attempts to attack her. During the uproar, Koyanagi manages to capture Ms. Yoshiyama and fly away. Large groups of walking machines attack Kaori, and Tadashi becomes lost in his attempt to save her. He continues to search for her, when he notices the circus troupe attack Koyanagi's airship, which deploys a set of wings and escapes. Tadashi encounters a group of students from Kyoto University, who explain that they are immune, and that the virus created the walking machines after synthesizing them from shipwrecks. He joins the students in their research to defeat the virus and save humanity. As the group walk together, Tadashi encounters Kaori's burnt