Original: (Aged 16) When the plot fails, Naraku revives Sango's little brother Kohaku, controlling him as a pawn to manipulate Sango's emotions and attack the rest of Inuyasha's group. Sango seeks vengeance against Naraku, but her primary goal is to rescue Kohaku from Naraku's influence and save his life.
Simplified: Sango's new aim is to also save Kohaku from Naraku's control.