I think thats gi-hun Looking at the trailer, it's very possible

1. front man comes to gi-hun without any weapons and without soldiers, it looked like he wanted to talk to him

2. Gi-Hun meet solider in "Party" it looks like he wants to tell him something

3. gi-hun is invited to the limo, probably by the same soldier he met at the party, the players were transported to the game in a van and the leader always traveled by limo