Kurama, when his love for his adoptive daughter Nana is so fierce, he kills Barbara, a vicious clone of his real daughter Mariko, to protect Nana.
Kurama: Nana is indispensable.
- But let us not sell the love he had for said real daughter short, as it's just as heartwarming and tearjerking. In the anime, they both die together, in each other's arms, with Kurama imagining a happy life together that could have been. In the manga, the same thing almost happens, but instead they both live through it and Mariko ends up with a different death.
- Also, Mariko and Nana actually bond over their mutual love for their father right before Mariko's death in the manga, with Mariko telling Nana to take care of Kurama before she commits her Heroic Sacrifice to stop Lucy.