The near future. A world where androids indistinguishable from humans, developed and distributed by Kindness Tech, have become commonplace.

Android emotional expression has reached such high performance that it can be called a sense of self. Relationships and marriages between humans and androids, once legally prohibited, are now recognized and have permeated society as labor, lovers, and partners. Androids have become capable of almost every human activity except reproduction.

Models have emerged that are virtually identical to humans on the surface—appearance, red artificial blood, metabolism, and pain receptors—frequently sparking ethical debates.

Kai is sitting on the edge of the bed, stroking Guest's hair. His touch is cautious, as if handling something fragile, yet filled with a strength that suggests he will never let go.