Kurotsuchi is a female shinobi who along with Akatsuchi escorts the Tsuchikage. She refers to Deidara as Deidara-nii (nii-san = big brother), either as family or a sign of respect.
In chapter 700, it is shown that she has taken over the position of Tsuchikage.
Bloodline limits (Kekkei Genkai) are special abilities or bodily constitutions passed down genetically. Here's a complete list of the bloodline limits that play key roles in this series by Masashi Kishimoto.
