Catheter, an editor who came to the office of popular young novelist K.G. Torato, who lives on the planet Karnov II, to receive a manuscript for a new serialization. However, his pet dog, Patrasche, died, and he has no energy to write the manuscript. The two of them head to a pet shop to buy a new pet, but the one who likes the catheter there is Teshigawara Sorsu, the 15th heir of the Teshigawara royal family, a Saturnian named Sorsu Princess!?