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...
What is that? A key?
ما هذا؟ مفتاح؟
Was ist das? Ein Schlüssel?
¿Qué es eso? ¿Una llave?
¿Qué es eso? ¿Una llave?
Sans déconner, une clé ?
E quella cos'è? Una chiave?
O que é isso aí? Uma chave?
Что тут у нас? Ключ?