The current head of the Vongola crime family. His age is unknown,but it is implied that he is becoming too weak to lead the family,which is why he searches for his successor. It is revealed that he has been plagued with problems concerning his legs, thereby limiting his mobility.He accepted Iemitsu's son, Tsuna, as the next head of the Vongola Family, but a fake IX that replaced him decided that Xanxus was more worthy to become the next boss. Not realizing this IX was a fake, Iemitsu argued, wanting Tsuna to become the 10th boss. Thus, the fakeIX sanctioned the traditional Vongola battle; those who wield the same ring will have a one-on-one battle.

The real IX was kidnapped by Xanxus, who had placed him within Gola Mosca, draining him of his life energy. When Tsuna sliced Gola Mosca's armor in half, the IX was able to use his flame to show Tsuna his past;the IX used to visit Tsuna when he was just a child.

In the future, he has been unaccounted for since the Millefiore Family raided the main Vongola headquarters. During Tsuna's training within Hibari's spiked ball, he appears in a vision with the other Vongola heads and is shown with a flaming scepter,his signature Dying Will Flame weapon. Seeing him in the vision causes Tsuna to believe that he may be dead. Like Tsuna and the first, the IX also knows how to use the Zero Point Breakthrough, using it to stop Xanxus' rebellion during the Cradle incident.

The Vongola IX's stamp is the Dying Will Flame; he marks documents with his flame, proving they are official.