The person hiding in the mirror was Illuso from the Hitman Team. Fugo ends up being dragged into the mirror by Illuso's Stand, Mirrorman. Fugo then summons his own Stand, Purple Smoke. Despite Giorno wanting to find Fugo, Abbacchio decides to go look for the key, since that was their mission. However, once Abbacchio finds the key, he also gets dragged into the mirror world...
Fugo! Now that he's outside, 
Purple Smoke can follow him!
فوغو! بما أنّه خرج، يستطيع باربل سموك
!اللَّحاق به
Fugo! Er ist nun draußen, also
kann ihn Purple Smoke verfolgen!
¡Fugo! ¡Ahora que salió,
Purple Smoke puede ir tras él!
¡Fugo! ¡Ahora que salió,
Purple Smoke puede ir tras él!
Fugo, ora che è fuori,
puoi seguirlo con Purple Smoke!
Fugo! Agora que ele saiu,
mande o Purple Smoke atrás dele!