Gokudera is convinced that the girl who calls herself Chrome is Mukuro in disguise, but Tsuna doesn't think so. Chrome thanks Tsuna for his trust by kissing him on the cheek, angering Gokudera. Tsuna decides that Chrome will fight as their Mist Guardian. Colonnello arrives with Falco, concerned that Mammon may be an Arcobaleno. After Chrome politely refuses a group huddle, the Mist Ring Battle starts. Chrome begins with a trident strike that literally makes ground-shattering illusions. Mammon strangles Chrome with tentacles, but they turn out to just be strangling an illusion. Mammon, no longer holding in their power, drops their chain. Fantasma morphs from a frog to a snake and circles Mammon's head. As Mammon floats into the air and their Arcobaleno Pacifier shines, Reborn deduces that they are the missing Arcobaleno: Viper!
*Note: Bold + Italicized = First Appearance