Fugaku Uchiha is a prominent figure from the Itachi Shinden narrative, known as the leader of the Uchiha clan and the captain of the Konoha Military Police Force in the hidden village of Konohagakure. He was bestowed with a fearsome reputation on the battlefield, earning the nickname "Fugaku the Demon Eye" from other nations during the Third Great Shinobi War. This moniker reflects the terror his abilities inspired in enemy shinobi, and his talent was often compared to that of the Fourth Hokage, Minato Namikaze, and the legendary Sannin. In the anime adaptation, it is revealed that Fugaku awakened the Mangekyo Sharingan during the war after witnessing the sacrifice of a close comrade who saved his life, an event that granted him this advanced ocular power which he kept hidden from his clan and village.

In terms of personality, Fugaku is depicted as a stern, serious, and deeply responsible leader, whose primary focus is the welfare and political standing of the Uchiha clan. While other clan members perceive him as a paternal figure, his youngest son, Sasuke, views him as a cold and distant man, largely due to Fugaku's overwhelming focus on his eldest son and prodigy, Itachi, as the clan's heir. Despite his strict exterior, it is noted that his wife, Mikoto, confirmed that Fugaku was privately proud and caring toward both of his children, though he struggled to express his affection openly. He carried a deep resentment toward the village leadership for the suspicion and segregation the Uchiha faced following the Nine-Tailed Demon Fox's attack, which led him to reluctantly support and plan a coup d'état to seize control of the village.

Fugaku's role in the story is central to the tragic conflict that defines Itachi Shinden. As the head of the clan, he orchestrated the coup d'état against the Konoha leadership, using Itachi's position in the ANBU Black Ops to gather intelligence for the Uchiha, unaware that Itachi had become a double agent for the village. His key relationships are with his two sons; he initially invested all his hopes in Itachi, training him personally and defending him against accusations of murder, only to later shift his attention to Sasuke after becoming disillusioned with Itachi's growing distance from the clan. The dynamic changed when Itachi taught Sasuke the Fire Ball Jutsu in a single week, finally earning their father's praise and affection. During the Uchiha clan massacre, Fugaku and Mikoto confronted Itachi in their home. Recognizing his son's path and perhaps feeling immense guilt and sorrow for his own failures, Fugaku chose not to fight back against Itachi, even though he possessed the Mangekyo Sharingan and was considered one of the few shinobi Itachi truly feared. He knelt with his wife, told Itachi that he was proud of him, and asked only that Itachi take care of Sasuke before dying by his son's hand.

Regarding his development, Fugaku is a character defined by the tension between duty and family. He evolves from a hopeful father nurturing a prodigal son to a desperate man willing to risk a bloody civil war for his clan's honor, and finally to a resigned parent who accepts death by his own child's hand as the only resolution. His notable abilities, as established in the source material, are formidable. Beyond his elite status as a jonin and master of Fire Release techniques, particularly the Great Fire Ball Technique, his greatest asset is his Sharingan. While his Mangekyo Sharingan is only shown in the anime, within that context his hypnosis abilities were potent enough to briefly trap even a master like Itachi in a genjutsu. Fugaku was also perceptive and strategic, anticipating the village's intentions long before the coup was set into motion, and his overall combat prowess was so respected that leader figures like Danzo considered him one of the "rare geniuses" and most audacious leaders the Uchiha clan had ever produced.