First clue

Exploration Stage: Christmas Hall
From: Juliette
Description: I know what's going on, Monami. The Snow Queen wants to destroy Christmas. But Santa Claus is in the way. But if people stop believing in Christmas, Santa Claus will lose his power. Then the Snow Queen can approach the magical fir tree and make wishes come true without anyone stopping her! In other words, to save Christmas, we must save Santa! Santa must have left some clues in the hall.
Completed: Well, a glass of champagne. Does it come with a letter written in mysterious symbols? Maybe I need to find some of these messages to understand the clues about Santa Claus.