Earth, many years after humanity has disappeared. At the Galaxy Tower Hotel in Ginza, Tokyo, hotelier robot Yachiyo and her robot colleagues patiently await their owner's return, and for the day when they might once again welcome human guests. However, the first guest to arrive in 100 years is an extraterrestrial. One after another, guests begin to arrive, but are they here to stay, to invade, or perhaps...?

(Source: Storia Dash, translated)