Killuka is part of Zoldyck family and also twin sister to Killua. Although they are twins, they are complete opposite to each other. When the family proud and hope much from Killua, Killuka feels deserted by her own family. In disappointed, Luka (Killuka) escapes from the mansion and lives by her own with her loyal servant, Kaname. Until one day, Illumi and Hisoka find her.