In the spring of Kyoko's first year in high school, Eiko, a girl like a sister to her, returns with her younger brother, Jiro.
The return isn't that big of a deal, but Jiro (self proclaimed super mad scientist) has it in his head that he wants to operate on Kyoko!
And, what's even more, the two of them are actually high ranking members of an Evil organization at the run from the heroes of justice!(well not as much as you would think)
So high school and her daily life is about to become a bit more exciting as these two begun living with her.