In order to gain the Vongola's Mist Ring and the right to be the next generation's Mist Guardian, Chrome and Mammon participate in the fifth round of the Ring Battle.
Tsunayoshi Sawada and his Guardians (sans Kyoya Hibari and the Mist Guardian) arrive at the gym, the location for the Mist Ring battle, but the Mist Guardian has not arrived yet. Gokudera assumes that it is Mukuro when Ken Joshima and Chikusa Kakimoto show up, but it turns out to be a girl called Chrome, who has an eyepatch over her right eye, drawing suspicion to her, as Mukuro's right eye was his Six Paths of Reincarnation eye. The Cervello then announce that the battle commences, with both illusionists, Chrome and Mammon, being as creative as they can to confuse the enemy. However, Mammon is able to break Chrome's trident, and when they do, she falls on the floor and her stomach starts to sink in. Mammon deduces that it is because she was relying on illusions to replace some of her internal organs. A mist covers the area, and someone chuckles. When the mist clears, it is revealed to be Mukuro, and he battles in the place of Chrome. Murkuro's powerful illusions win against Mammon, nearly killing them, but Mammon saved just enough energy to escape, betraying the Varia. However, with Mukuro's Flames spent up, he returns the body to Chrome, once again restoring her illusionary organs.
Afterwards, Xanxus orders Gola Moska to eliminate Mammon afterwards. Mukuro slyly states to Xanxus that he feels awed at the scheme that Xanxus thought up, but wouldn't say anything, as he "wasn't a good person." Mukuro then returns the body back to Chrome. The Cervello then announce that the Cloud Ring Battle was next.