Hikaru is the oldest of the twins, his other brother being Kaoru. Hikaru has an immense attachment to his younger brother and shows extreme anxiety when seperated from Kaoru. The two seem inseperable and yet when together their confidence increases dramatically. Hikaru's behaviour can range from unpredictable protectiveness of his sibling, yet when seperated Hikaru shows intense levels of stress and fear. Fear based aggression is present especially towards strangers or unfamiliar Tokotas. This can be counteracted through social training, behaviour correction and bonding.