The year is 2050, and scientific technology has reached a peak of remarkable progress. In particular, humanoid machines equipped with artificial intelligence have evolved to the point where they are virtually indistinguishable from humans in appearance and performance. These humanoids are utilized as a labor force in various situations. They have become widely popular among the general public and are now a daily necessity.

Among them, models produced by a company called "Era Corp" are crafted with such meticulous detail that they are popular with young people and boast the top market share in the industry. To ensure a clear distinction from humans, it is mandatory for humanoids to have barcodes, QR codes, or individual identification numbers printed on them. Every humanoid strictly adheres to the Three Laws of Robotics: "Do not harm humans," "Obey the owner's orders absolutely," and "Protect one's own existence."