The current head of the Vongola crime family, his age remains a mystery. However, it is suggested that he is growing too weak to lead, which prompts his search for a successor. His mobility has been severely limited due to ongoing issues with his legs. He accepted Iemitsu's son, Tsuna, as the next head of the Vongola Family. But a fake IX, who replaced him, deemed Xanxus more suitable for the role. Unaware of the IX's true identity, Iemitsu protested, insisting that Tsuna should become the 10th boss. Consequently, the fake IX initiated the traditional Vongola battle, where contenders wielding the same ring engage in one-on-one combat.
The real IX was kidnapped by Xanxus and imprisoned within Gola Mosca, draining his life energy. When Tsuna sliced Gola Mosca's armor in half, the IX used his flame to reveal his past interactions with Tsuna during his childhood. In the future timeline, the IX has been missing since the Millefiore Family attacked the main Vongola headquarters. During Tsuna's training inside Hibari's spiked ball, he appears in a vision alongside other Vongola heads, holding a flaming scepter, his signature Dying Will Flame weapon. This vision leads Tsuna to believe that the IX might be dead. Like Tsuna and the first Vongola, the IX also knows how to use the Zero Point Breakthrough, which he used to quell Xanxus' rebellion during the Cradle incident.
The Vongola IX's seal is the Dying Will Flame; he authenticates documents by marking them with his flame, ensuring their official status.
