Hiashi Hyuga (日向ヒアシ, Hyūga Hiashi) is the head of the Hyuga Clan. He is the father of Hinata and Hanabi Hyuga, twin brother of the late Hizashi Hyuga, and uncle of Neji Hyuga.
As the father of Hinata Hyuga and the uncle of Neji Hyuga, Hiashi has a significant role in the lives of his daughter and nephew.
Hiashi was born seconds before his twin brother Hizashi Hyuga, making him the head of Hyuga clan. The fact that Neji would never be able to succeed the clan, and that he would be marked with a curse mark so that he could be disciplined caused friction between the brothers.
On Neji’s fourth birthday, Hiashi personally placed Neji’s seal on him. When his daughter, Hinata, was kidnapped by a the Head Ninja of Kumogakure no sato, who was acting as an ambassador to Konoha at the time, he had no choice but to kill her kidnapper. The Land of Lightning overlooked the kidnapping, and they demanded a life for a life, asking Hiashi surrender his life and be killed, or else a new wave of warfare between the Hidden Leaf and Cloud villages. While Hiashi planned on accepting the punishment, the Hyuga Clan elders new this was merely another attempt by the Land of Lightning to get their hands on the Byakuga. The elders instead suggested that Hizashi go in his place as not only could they claim it was killed the Lightning Ninja, but it would be impossible to get any information from Hizashi's body thanks to his curse mark. Hiashi immediately refused the idea, until Hizashi stepped forward revealing that it was his idea, saying that while he hated the main family's foolish laws, he wanted to save his brother and decide his own destiny. He asked Hiashi to tell Neji about his decision and his reasons before leaving to be killed.
Originally, Hiashi had trained Hinata to become the successor of the Hyuga Clan, but Hinata’s lack of confidence ultimately led him to deciding she was not worthy and instead turned his attention to his younger daughter Hanabi while leaving Hinata in Kurenai Yuhi’s care.
Hiashi's general personality is very stern and strict, as he assigns both his daughters arduous training, rarely complimenting their performance. This is especially true with Hinata; when she was assigned to Kurenai Yuhi, he told her that he was unconcerned about the possibility that she would die, saying that the Hyuga Clan had no use for a weak successor. In truth, it was not that he felt Hinata's talent or potential was weak, but her drive to succeed was too weak to be the successor of the Hyuga Clan. Upon seeing her show true dedication, he began to openly cheer her on.