On a particular night, an unexpected guest suddenly turned up outside science fiction magazine editor, Obinata Taiga and his family's home! The person was actually Asuoo Shuu, who had married their elder sister; the dictator of the family, and since became their brother-in-law. What's even more incredible is that he is not only the writer that Taiga is responsible for, but was also Taiga's high school classmate! But, just when everyone was vehemently expressing their objection to Asuoo, they received news that their all-important sister has gone missing! Out of ideas, Taiga had no choice but to let Shuu stay on, they could only wait until their sister comes back to decide everything!