[i]Pf, My trick must not have worked as well as I thought. There are still two that shouldn't be here. I'll have to make changes to my plan...[/i]

Prospero just kept smiling despite the setback, Cyril's threats and Naoto's obvious anger. "ooh, scary scary!~ But I thought you would already have the trick all figured out by now, though. Maybe my information was wrong, and the Vongola aren't as useful as I thought they would be..."

 At this he feigned walking back toward the space he'd initially appeared from as if he was just going to vanish in a burst of flame and smoke like he'd initially arrived. Mist and smoke suddenly started flowing out from under the stage and Prospero turned around to face Naoto and the rest again. "But if you really want to know who I am and what happened to all of those innocent audience members...I guess I could demonstrate!"

Prospero threw his arms wide as the Mist from the stage seemed to surge forward with the motion. From the perspective of Michael, Arty and the other guardians, it would seem like Prospero and Naoto had suddenly both disappeared. From Naoto's point of view though, everyone around him would disappear, leaving only the mists behind. 

"...Fufufu~ Still confused, [i]Vongola Undecimo[/i]?" Prospero formed himself out of the still lingering mists in front of Naoto as he spoke up "How about this? If you can see through my tricks or beat me in a fight, I'll bring your friends back and tell you everything I know! But if you lose, you have to agree to my demands."

Either way, Prospero would see for himself what sort of Boss Naoto was before he went ahead with becoming his Mist Guardian.