Ai no Idenshi begins in a future world where human-like androids, known as "Humanoids," coexist with humans. The pilot episode, titled "Backup," introduces viewers to a society where approximately 1% of the population consists of these Humanoids, distinguishable from humans only by their eyes.

The protagonist of the episode is Hikaru, a doctor raised by a Humanoid mother. The plot takes a deeper turn when we learn that his mother willingly copied herself to provide medical treatments for Hikaru as a child. However, this act was deemed illegal and led to severe consequences, including her being forced to manufacture traditional wooden sandals, known as Geta.

Hikaru now runs a clinic where he treats both humans and Humanoids, but his work with the latter remains under the radar. One of his patients is a Humanoid woman infected with a virus after her Humanoid husband used illegal technology to create a backup of her. This illegal act forms the basis for the profound ethical and philosophical dilemmas the series aims to explore.

A critical discussion arises when the only way to save the Humanoid woman is to restore her from an uninfected backup, causing her to lose a week's worth of memories. This situation raises profound questions about consciousness and identity. It is clear that Humanoids are sentient beings like humans, and thus, the woman is deeply concerned about whether this restored version of herself would truly still be her.

The episode ends on a fascinating note, leaving viewers with the expectation that these philosophical questions will be further explored in future episodes through Hikaru's clandestine medical work on Humanoids. As a series, Ai no Idenshi appears to use the hard science fiction genre to reflect on fundamental questions of humanity in a society where the boundaries between humans and androids have been blurred by technology.