Skull is first seen in his assault on Mafia Land for the Carcassa Famiglia. He faced off against Reborn, but lost horribly when he was made unable to give commands to his pet octopus. Colonnello simultaneously obliterates all his sea forces.
In the Future, Skull is said to have died. The Millefiore Famiglia second-in-command and current Sky Arcobaleno, Uni, possesses his Cloud Pacifier. After Byakuran has been defeated, Skull returns alongside the other Arcobaleno.
During the Arcobaleno Trials, Skull is second to test Tsunayoshi Sawada. He hires Viper to disguise himself as Tsuna in an attempt to lure both Kyoya Hibari and Mukuro Rokudo out to fight the real Tsuna. Upon witnessing Tsuna's Hyper Dying Will Mode, Skull frightfully admits that Tsuna looks much stronger than he was during the Mafia Land incident. Tsuna uses X-Burner to defeat Skull's Armored Octopus. He then presents Tsuna with his seal. After doing so, he tries to sneak away; however, he is beaten by Reborn and Colonnello for bragging about how impressive his method was before the trial. He later helps out in the fight against Verde, though his ship is easily destroyed by Box Weapons mistakened for missiles. He is captured along with the other Arcobaleno, though his helmet protects him from the radiation similar to the Anti-Tri-Ni-Set until Verde removes it.
Skull and the other Arcobaleno are called by Reborn to train Tsuna and the others. He is paired up with Hibari, as the both have the Cloud Flames. Hibari is shown to intimidate Skull, and Skull is shown to irritate Hibari, creating a caustic relationship. Later, at a meeting of the Arcobaleno tutors, he tries to tell of his training with Hibari, but is interrupted by Reborn before he can do so since Reborn knew that he was afraid of Hibari.
Afterwards, while Hibari was sleeping on the school's rooftop, Skull approaches him after finally finding him. He starts boasting about him being Hibari's tutor and there will be nothing he has to worry about. Although he is easily frightened by a demand Hibari made, but after he realizes that he was supposed to be the one giving out demands, he decided not to obey him. Annoyed by this, Hibari stood up and threatened to bite him to death, causing Skull to run away.
After Yamamoto, Lambo and Gokudera had taken their Trials, Alaudi appears to give Hibari his trial. Hibari immediately loses interest after hearing that there will be no fighting in the trial. Alaudi lets Hibari know the rules of the trial and disappears. Skull overhears the conversation and tells Reborn and the rest. After Tsuna and company failed to convince Hibari to take the Trial, Reborn tricks Skull into action. Skull interrupts the fight between Ryohei and Hibari with his airship, threatening to fire the cannons at Hibari if he refused to take the trial. Hibari and Ryohei manage to fend off Skull's attacks. Hibari then pierced the airship with his Porcospino Nuvola ver. Vongola, causing the airship to lose control and almost to crash into Namimori Middle School.
After Byakuran was defeated, Skull and the rest of the Arcobaleno were revived because Uni sacrificed herself to bring them back to life.
Skull is seen in a dream with all the original "I Prescelti Sette" in their adult forms. Suddenly, Luce and Lal Mirch disappear, with only Colonnello replacing them. The Arcobaleno all voice their confusion, when the man with the iron hat they met before becoming Arcobaleno asked them if they wanted to be freed from the Arcobaleno curse, Skull, along with the Arcobaleno except for Reborn, voicing his agreement. The man with the iron hat then explained how the person chosen to be turned back would get the opportunity; they had to fight to determine the strongest Arcobaleno. Verde expresses his disagreement, stating that even a baby would know the winner of a battle between a scientist and a hitman. However, the man with the iron hat states that they would pick representatives to fight for them. Reborn voices his distrust of him, the man with the iron hat angrily stating that he would leave and they would be in their current forms forever in response. However, Skull, with all the other Arcobaleno except for Reborn, agreed to the fight. Reborn, feeling pressure, agreed to it as well. Skull, however, piped up that he was unpopular and no one would fight for him. However, the man with the iron hat stated that he had prepared "emergency options" if they didn't find a representative. The dream ends, leaving Skull to go the next day to the riverside to feed Enma's cats, demanding him to fight for him in return for feeding the cats. Skull is later on seen asking the Simon Famiglia's transfer students to help him in their home, various members dissuading Adelheid to agree as well as scoffing at his bold claims of previously being in his adult form a "pretty-boy hottie" and "seven heads tall", which made Julie imagine an ugly adult-Skull. Later, Adelheid agrees, though misunderstanding, telling Enma to tuck Skull into bed.
Later during the first day of the representative battle, Skull watches as Enma fights Varia alone. Enma was losing, and Skull was worried about the former's safety; suddenly, he remembered the reminder Tsunomichi gave about the "present" activation, which gives the Arcobaleno a "present" that the man with the iron hat prepared. Skull makes use of this and speaks the words necessary: "present, please", and the Arcobaleno curse is removed from him, also allowing him to join the battle. However the match ends before he is able to take action.
On the second day of battle, Skull was just playing around, as no one had challenged his team, when suddenly the Vindice attacked them and severely injured his representatives. Skull, frightened, asks them who they were and calls them thieves after they take his representatives' Rainbow Wristwatches, but is punched through his Purifying Helmet by Bermuda von Veckenschtein, who then takes his wristwatch.