Two siblings bounded by fate have the same father, but with two different relations of mother's.
They fall in love and discover mysteries of their father which unravel their solutions as siblings.
Chichi and Goku are having another child. But unlike the two boys there's something different, not only is their third child a girl but their having twins. One boy and one girl. Soon after the twins are born one becomes very ill with something unknown. As time goes by Goku's daughter shows the doctors that they were wrong!