At some point before the war between the Vongola Famiglia and Millefiore Famiglia, the Giglio Nero Famiglia were in the process of fighting the Gesso Famiglia. During this time, Aria died due to her position as the Sky Arcobaleno, as all Sky Arcobalenos are cursed with a short lifespan upon taking the Arcobaleno title. Her daughter Uni took over the role and, after a short conflict with her, Gamma soon grew close to her. After a deal with the Gesso Famiglia failed, Uni and Byakuran met to try and end the conflict. However, Byakuran used a powerful drug to suppress Uni's will, making her agree to the merging the two Famiglias into the Millefiore Famiglia and the surrender of their Mare Rings. After this event, Gamma gave her his strongest Box Weapon, stating that he would only use it when fighting solely for the Giglio Nero Famiglia.
While stationed in Japan, Gamma was ordered by Shoichi Irie to locate the hidden Vongola base. While searching Namimori, he engaged the younger versions of two Vongola Guardians who had been brought to the future, Takeshi Yamamoto and Hayato Gokudera, whom he easily defeated. After torturing the two, he discovered that the Vongola boss was still alive. Gamma was attacked by the future Kyoya Hibari and was defeated, only after confirming with his own eyes what he had discovered during the interrogation. Gamma was later revealed to have survived his defeat, which he was greatly angered about. He was visited by Genkishi, whom he greatly loathed due to his betrayal of the Giglio Nero Famiglia. Despite this, Genkishi relayed the message from Uni that "the time has come", and returned Gamma's Box Weapon.
Merone Base Invasion Edit
While stationed at the Merone Base, Gamma was told to guard the control room from the Vongola invasion. However, due to Shoichi, the base moved so that Gamma encountered Ryohei Sasagawa and Hayato Gokudera at the training room. Gamma was capable of defeating Ryohei, who had chosen to fight alone, but was baffled by Gokudera's Sistema C.A.I. The battle ended in a huge explosion that knocked the two out. Later, Gamma was rescued by Tazaru and Nosaru.
When the Vongola returned to the past for the Arcobaleno Seals, the present Gamma, who was still a member of the Giglio Nero Famiglia, had been ordered by Aria to guard the girls, Kyoko and Haru, during Verde's trial. He also encountered Bianchi, who soon realized that he wasn't a threat. He later returned to Italy with Aria.
Later, when Uni defected from the Millefiore and escaped with the Vongola, she was taken by Torikabuto. Gamma then revealed himself and took her back with Tazaru and Nosaru. They later joined the Vongola in fighting the remaining Six Funeral Wreaths, though Gamma was easily defeated after Zakuro used his Asura Box. Later, during Tsuna's final fight with Byakuran, Gamma was able to jump through the cracks in the Tri-ni-sette Sky Barrier. He then joined Uni, who was sacrificing herself to revive the Arcobaleno, to provide his own Dying Will Flames, and accompanied her into death, reversing all of Byakuran's misdeeds in other parallel worlds.
Gamma walks back to the Giglio Nero Famiglia's mansion with Nosaru and Tazaru. Suddenly, Aria's Orange Arcobaleno Pacifier starts emitting powerful Sky Flames, shocking them. Byakuran then reveals his present self and the other Six Funeral Wreaths, stating that it was emitting Sky Flames due to finding a new owner. Gamma questions Byakuran's presence and motive, but Byakuran simply replies that they were going to work together to dispel the curse of the rainbow. A figure then walks from the forest, the Pacifier's Flames growing even more powerful and flying towards the figure. As the figure is revealed to be Uni from ten years in the future, Gamma, Tazaru, and Nosaru gape in shock.