The player takes on the character of Ichihiko in the game. At first glance, he appears to be a reasonably ordinary young man living a (nearly) regular life. He lives at home with his two sisters, Mizubashou and Shirotsumegusa. He frequently quarrels with his next-door neighbor Hinagiku, attends school with all three, and spends his days living in a nearly perfect environment. Of course, there are some peculiarities.
To begin with, Ichihiko, his older sister Hinagiku, and their teacher, Kobatomugi-sensei, appear to be the only humanoids in the universe. Everyone else resembles ancient sci-fi movie drone robots known as Saberhagen-class droids, which speak by repeating the phrase “oui monsieur” (and are understood the same way Star Wars characters understand R2-D2’s beeps). On this planet, it never rains, and the weather is always convenient. Where Ichihiko’s favorite shows and dishes are always on TV and supplied, yes, this world is a sham. As the story progresses, the player learns that Ichihiko is the “last mankind” (the last human left in the universe). The robots on the starship Saint Exupéry-go discovered him in a stasis capsule. Feeling that he is too young to govern the ship and play his part in bringing about humanity’s second coming, the robot R-Mizubashou suggests that he be awakened and raised by them, and that a suitable “happy” world be built just for him, a world where he has a loving family, a large number of friends, and feels no hardships or pain. After being without humans for nearly millennia, the robots draw on almost every possible source to create Ichihiko’s perfect world. To do this, they’ve used data from “older” robots on board, books, movies, and even manga. While most of the robots engaged knowingly continue the illusion (and do everything in their power to eliminate dissenters), others desire to inform the “last mankind” of reality.