Plastic Memories takes place in a city in the near future, in which humans live alongside androids that look exactly like humans and have human emotion and memory. SAI Corp, the leading android production company, has introduced the Giftia, an advanced android model with the most human-like qualities of any model. However, there is a catch. The lifespan of a Giftia is determined beforehand, and a Giftia can only live for a maximum of 81,920 hours (roughly nine years and four months). If they pass their expiration date, it causes personality disintegration, memory loss, and outbreaks of violence; those who experience this are known as wanderers. Wanderers only act on instinct and can no longer recognize their owners. As a result, the Terminal Services are established with the duty of retrieving Giftias who are close to the end of their lifespans from their owners, and erasing the Giftias' memories. To perform this job, the Terminal Service employees work in teams consisting of a human (called a "spotter") and a Giftia (called a "marksman"). The story follows the work and life of such a team in SAI Corp's Terminal Service One office, the human protagonist Tsukasa Mizugaki and a Giftia named Isla. Slowly, their relationship progresses, and as both slowly fall in love, Isla is revealed to be nearing the end of her own lifespan.