Hibari pushes Fon out of the way, telling him that he could handle Team Mammon. Superbia Squalo, however, tells Hibari to wait, as if he destroyed his Boss Rainbow Wristwatch, he wouldn't have a chance again to fight an Arcobaleno. Squalo invites Fon and Hibari to simultaneously take him on, but is cut off by Xanxus, who spits mochi at him to quiet him down. Mammon recalls that he got Xanxus to come by waking him up, Xanxus being hungry. Mammon then said that there was food in the kitchen, but then mochi got stuck down Xanxus' throat. Mammon ran off to "help" him, and Xanxus chased after him, leading to the current events.
Mammon warns Xanxus not to listen to the "preaching" of Fon. Fon expresses his confusion, so Mammon reveals that when Fon reprimanded him for being attached to money, he always got irked. Fon, though, adds that he thought that using money to buy new Varia Rings was legit. Mammon tells Fon not to act superior, asking rhetorically if he thought martial arts was better than illusions. Mammon expresses his anger at past events when Fon would converse about martial arts and such while Mammon slept. Mammon cuts himself off and sums up his point by telling Fon that he hated him and that he would win the Representative Battle of the Rainbow to return to his original form. Xanxus promptly kicks Mammon out of the way, and Team Fon and Team Mammon do battle.
Dino, meanwhile, by the door, notes that Byakuran was defeated and that Tsuna went to fight Iemitsu Sawada alone. He then notices the fight between Team Fon and Mammon, noting that it was a super high-speed battle. The two teams trade blows, and then break the hotel's windows. Mammon is amazed at the power, but knows that they were just testing each other. Mammon is surprised to see that out of the attack, Fon was the only one that got hurt. Fon confidently states that the exchange just then was to adjust to his larger body and announces confidently that his next movements would happen in microseconds, and be accurate to microns. Fon then uses his Exploding Gale Fist, his invincible fight style. In response, all three other combatants release their Box Weapons. Fon mentally states that he was impressed with Xanxus and Squalo's fighting, but states that he couldn't hold back as there wasn't enough time. Fon then uses Exploding Dragon Fire Dance.
However, Fon suddenly falls down, his body heavily cut. Fon realizes that Mammon created "rules" inside his mind, and when broken (the rule being that he was forbidden to use Exploding Dragon Fire Dance), heavy damage would be caused to his body. Fon identifies it as Hyper Mirage R. Mammon confirms this in his un-cursed form and announces that the next rule would be that anyone on the battlefield that had doubts about their victory would self-destruct.
Note: Bold + Italicized = First Appearance