Kaori is Tadashi's girlfriend. She has an extremely sensitive nose and becomes very jealous when Tadashi is near other women. Near the beginning of the series Kaori started noticing the odd smell. She and Tadashi tried to escape and went to Koyanagi's lab. Due to her overly sensitive nose, she seems to be able to sense when the creatures are coming. However, she is later infected, causing her body to swell up and be covered in boils.
The germ also forces the gas with the "death stench" out of her body. Because of this, she began to think she was disgusting, that Tadashi wouldn't love her if she wasn't beautiful, and she would never be healed. This, along with the horrible stench, made her hang herself from the wires of a ceiling lamp. But the wires were weak and could not support her additional weight with the gas bloating her. Tadashi then immediately carries her to his uncle Koyanagi's lab for aid.
It turns out Koyanagi rigs her up to a custom walking machine. Ultimately, she becomes like the walking dead creatures, except for one quality - she has a will of her own. Later she was captured by the Citrous Circus, whose ringmaster was using the infected creatures and humans along with the gas, as attractions.
Kaori escaped and fled. Tadashi dragged her back to Uncle Koyanagi's lab . But when she escaped outside again after thinking Tadashi was now attracted to Ms. Yoshiyama, she was attacked by the other creatures. It is likely that this was because they saw her man-made walking machine as a threat to their existence. Near the end of the series, Tadashi finds her burnt corpse, commenting on how she is 'finally rid of the smell'.
She lives in Kokubunji.