Little is known about Seto except that she is Rei and Takashi's neighbor and that they both seemingly know her.
Seto has only been seen as one of "Them". She has long hair tied in a loose ponytail with the front combed down along with a small strand near the center of her head.
Nothing is known about Seto's past except that she was Rei and Takashi's neighbor and that they have apparently known her for some time and a notably size-able bust.
Nothing is known about Seto's personality.
Seto is first seen in Tanaka's front yard with another one of Them when Alice goes to check out the house. She slips and falls, causing her to attract the attention of Seto and the male zombie. Seto is about to attack Alice when Saya hears her screams and comes to her rescue. With Seto in her sight, Saya fires her MP5SFK but does not kill the undead, only blowing a hole through her chest. Saya swears "Stupid sexist bullet!" and keeps firing, still only grazing Seto's shoulder and hip. Takashi and the rest of the gang run into the yard and identifies Seto as one of their neighbors. Saya tells Kohta and the others not to help, saying that she will kill Seto with the next shot. Proclaiming that she is "the smartest genius ever", Saya finally hits Seto's head, killing her permanently; all while Saeko tells her that she does not need to shoot anymore and kills the male zombie. A brief moment later, Takashi tells Saeko that she was right earlier by saying that it was too hard for him and Rei to kill their neighbors, which is why they did nothing to help in killing Seto.