When Mikio Natsuno obtains a residency certificate, he is stunned to find the name of a woman he has never met listed as his wife. Apparently, he has been "married" for six months without knowing it. Who on earth is the stranger who decided to become his wife? After a frantic search, Mikio finally discovers her—an eccentric young woman with a striking personality who simply says, "I thought I could keep myself together if I were at least married," offering no further explanation. And so, their uneven, unpredictable relationship slowly begins to take shape.